There is recommended cleaning carpet with some dish soap, cotton towels, a steam iron, and careful technique. I have done carpet cleaning and will probably be doing more. Overall it's a pretty good video, but I wish to give some caveats:
You need to be careful about chemicals used on carpet; if you have the manufacturers' recommendations, know who your manufacturer is so you can find them, or know what kind of carpet it is so you can research recommendations for the following:
1. Material type.You need to read up on how to properly clean the carpet. Soap tends to be basic, and some materials should not be cleaned with basic solutions; others should not be cleaned with acidic solutions; getting it wrong way may remove chemicals applied for stain resistance so that perhaps this first stain of yours came out because the soil was around the fibers, but with their coatings remove the next stain may go (permanently) into the fibers and not be removable; you might also discolor the carpet.
2. Material generation/specific characteristics.
3. Chemicals applied to the carpet for its protection
Carpets can be one of five generations of Nylon; it can be Acrylic, Rayon, Cotton, Wool, Various kinds of sisal and jute (sometimes used only in backings), Polyester, etc.; it can be mixes of any of these, making cleaning more complex. And often one (untrained) cannot tell simply by looking at or touching it. (But even trained people might have to perform various tests either to determine type, or determine what's safe to use on it.)
Because they have to have many characteristics (e.g. resist water based stains, resist oil based stains, not be destroyed--e.g. unravel or bloat or else--by spills, maintain form under pressure, tread, and crushing for years, expand and contract with the environment but not too much, etc.), carpets are complex in a way. They're everywhere (at least in America), and have to be sophisticated enough to be something that can be tread upon constantly, crushed under furniture, spilled on, and generally just take abuse, but (as some southerners put it) "keep on keeping on" in spite of carelessness, neglect, under- or lack of maintenance, and all despite that their use is constant.
Centuries of weaving techniques are embodied in their construction; billions in materials and chemical R&D in their fibers and shape; their backings are mixtures of various materials to give them all sorts of properties and what exactly is in there can vary considerably; the very characteristics of the fibers themselves, not just material types and chemicals present, can matter to cleaning properly (i.e. not causing damage). I worked for one company that had a one-size fits-all approach and wanted us spraying silicon soil retardant/sealer indiscriminately, advertising how "gentle and nontoxic and green it is, though more expensive, than the kind of stuff typically used"; the problem is that there are some materials that one should not apply any kind of silicon to, period! And the business owner would have known this after decades in the cleaning business. I stayed there only a week and a half.
Thus my favorite comment to this video is:
And another, that starts to show it's more complex than "if you have a stain, use dish detergent":
Use an ammonia solution, wet towels and an iron, Follow the same procedures outlined here. Only the chemical changes. You are talking about cat food upchucked by the cat. That stain is a mix of stomach acid and Red Food Dye #4 which only ammonia will get. I have a carpet cleaning company and we use something called Red Out which basically is ammonia.Even this, however, can be a bad idea: one should not apply Ammonia indescrimnately!
The unfortunate truth (one that sucks) is that the manufacturers don't design carpets which take soils from animals or other substances to be cleaned by the ordinary Joe or the amateur. The manual the homebuyer almost never receives always warns to obtain professional services by knowledgeable professionals. Carpets just aren't as simple as they appear. To make it easy they usually say "steam-extraction cleaning only", though honestly bonnet and brush-scrubbing methods, if done right, where appropriate, by a discerning cleaner, can also be employed (but again, where appropriate as determined by someone who knows what he is doing: "steam only" is a bit of a simplification: I've done both, and will continue to use both, depending on where
I cringe when people go get those underpowered shampooers from the grocery, or local home improvement store, that can't extract enough solution to prevent worse soiling because residues are left, which are correlated with much significance to various mysterious illnesses (especially in children); there just "ain't no way" any sane business will sell or rent high powered suction equipment to people who aren't in the business: it is dangerous, and takes special handling, care, experience...without which one might electrocute oneself (with certain machines), blow-out a powerful motor with some pretty simple-to-make mistakes, and so on: it's all just too much liability.
Some months back we went to a house with carpets that looked just awful, and then spent more time extracting do-it-yourself-er shampoo than dirt, with pass after pass more foam bubbling up, and I sat thinking to myself how normally we might *want* (and probably could) to charge the customer for the extra labor: we're there to do various passes in certain directions for dirt and spills, not four times the effort to fix customers' own attempts at cleaning; I don't know anybody that tends to, but instead this lets one show customers why cleaning machines (besides vacuums) available to the average person are such a terrible idea (it's this extra residues that, besides posing a health threat, cause the carpets to become so darn dingy): when she said that she had tried removing the dirt and stains herself with rented shampooers, we could actually tell her before that we would probably be pulling out a bunch of residual shampoo, and as she watched the shampoo come back out (that she thought she had extracted), explained the threat to tenants' health and overall cleanliness: this was not someone who we would ever make much money off, either, and from a business perspective compared to our normal rates makes no sense to schedule, being she gets the friends-and-family "discount" (practically free and barely covers expenses, pay for time being a drastic reduction from normal or minimum desired/fair, etc.).
As for this video, ironing probably won't remove all the soiling of a very wet stain, for the same reason his stain came back the next day after the first cleaning: pollution passes straight through the carpet, rather than just sticking and going in to the fibers, so by cleaning the surface, the fibers wick some of what passed through back to the surface. The material that passes from the surface to below also tends to spreads (or tends to) underneath in the sub-floor, in the backing and so forth. What this means is that one should not clean just the spot, but all around it, but the area around it where soiling is not visible probably cannot be reached with this method: it is spread underneath! If you have ever ripped-out nice looking carpet in a mysteriously smelly house, you discover how far animal stains can go in those invisible places! (And, unfortunately, release the rest of the smell for your enjoyment while on the job.) And all that organic material becomes a smorgasbord and comfy home for bacteria to thrive on and make generate the odors.
So there you go, caveats.
Don't tell those I work with that I said this, but you definitely shouldn't spend your last ninety, or (depending on house size) several hundred, dollars on getting professional cleaning (of course a constantly incontinent dog that keeps hitting the same places might be an exception: I had one of those about a month ago, and recommended that they get a nice large, climate-controlled, dog house to make the old boy a permanent outdoor resident safely, to preserve their high-end dollar flooring materials).
Animal stains can actually be among the hardest things to clean. And heck, coming behind and cleaning after some DIY-er thought they did well by using an iron on the visible portion of a spill or animal stain often means, once professional equipment and techniques have disturbed any subfloor staining that was set before, that "new" stains will appear, i.e. really they are old, but they may never have been visible in the places they appear, though often a stain like that cleaned in this Youtube video also tend to reappear because material trapped further below was not extracted by the iron.
Whenever a spill or stain occurs, notate the kind and location, the date* that it occurred, and what you did about it. (*How long something has been in carpet can matter to proper cleaning, and even indicate if it's even possible: and don't lie, because once materials and soil are known, long-time cleaners have a good sense about whether or not it will be removable, and if they find it's not but you said it was very young, they know the materials aren't lying; we may not call someone a liar to their face, but it certainly is useful to have someone insisting this when you know that, giving you insight on someone without them knowing you have it.)
All this information can help to insure the highest quality of cleaning is accomplished. E.g. at another recent job a spot appeared and kept reappearing incessantly; the customer swore they never saw it before at first, and that they hadn't seen after the last cleaners hired had come the year before: the funny part was that they didn't seem to remember that they...was us! (disclosure: I am from the South, and not making fun of African American Vernacular, as some might perhaps take it: actually their vernacular is a legitimate dialect that is highly interesting!!!! And these customers were not African Americans.) Eventually someone admitted to maybe spilling cooking greast. Someone had cleaned the surface and thought the mess was cared for, but along the lines as already explained, it wasn't fully dealt with. I stayed and cleaned, and re-cleaned and re-cleaned, until the wicking had all ceased. (You might wonder why we didn't use steam cleaning? Actually it would have made no sense for the circumstances: with one tenant of the apartment being home bound they couldn't do steam, which would take too long to dry and pose hazards to her; therefore a scrub, encapsulation, and extraction method was used.)
So there you go! G'luck!!! Happy cleaning.