Sorry for the long delay in writing, I just haven't cared for a while.
Youtube Poop is one of the top 10 things ever created by man. If you have not seen one, you are missing out. The premise behind a Youtube Poop is to take something and use video editing techniques to make it dirty. For example, making Spongebob kill people or Twilight Sparkle have sex with Spike. Like most things on Youtube, there are good ones and there are bad ones but lately technology has improved to the point where poopers are creating some incredibly high quality videos.
Most people looking for Poops the first time will find them made from footage of old Mario and Zelda CD-I games for the Phillips Laserdisk. The games were incredibly lame and the footage even worse but these videos are present in nearly all early poops and gave rise to the memes "My boy", "All Toasters Toast Toast", and "I wonder what's for dinner". The Mario animated series are also topics of many early poops and gave rise to some of the early speech twisting resulting in Mario saying "Shit". Today however, Youtube Poops have gotten incredibly advanced and moved on to essentially all subjects. Children's television is the biggest target with poops of Spongebob, My Little Pony and iCarly being widespread.
The Crap Door - Trololol'd
Possibly the best Youtube Poop ever made and illustrates all of the elements of Youtube Poop.
Youtube Poop, like many types of videos, has stylistic elements that are typical to the genre. Poops rarely use all of the elements but they easy enough to recognize after watching a few good ones.
Speech Twisting - Early poops straight swapped audio from other things onto video to make it appear that characters were saying something they were not. However, more current poops actually twist multiple syllables together to create new words that the character appears to be saying in their own voice, usually swear words (As shown in the above video when the narrator says "overworked servant of the fucking thing upstairs). This element creates hilarity because we have a character swearing when he shouldn't. The Crap Door uses a lot of speech substitution as well like when the skull says "Oh god, it's a book of PORN, you don't want to fap with that sort of thing." Using speech twisting the editor has managed to make the video tell a completely different story than it should have. In one of my favorite MLP poops the author remixes some speech in the opening sequence to make it sound like Twilight Sparkle says "I used to suck my brother's meat. Oh shit it's Mr. Clean." I die every time.
Repetition - Obnoxious repeating is a very common element of Youtube Poops. Some poops overuse this element to the point of annoyance but the video above does it perfectly multiple times as shown when the character Berk is looking through stuff and picks up the book of PORN multiple times, the crap door squishes the spider many times and Berk runs down the hall over and over. Repetition is an important comedic element but it is also one that bad poops abuse badly.
Swearing - All good poops have swearing, they just aren't as funny otherwise. How real the swearing sounds makes a really big difference and whether or not it's in the character's actual voice. Just tacking in swear words isn't nearly as funny as hearing a character like Patrick Star say "Spongebob, let's fuck."
Out of Control Visuals - These are becoming more common and add a lot of style to poops. Altering the original video is a very advanced technique and is a hallmark of a truly good pooper. I've actually seen a poop where the author was able to make it look like Spongebob was killing everybody he works with. It was excellent and highly stylized.
To end, I'll post the links of some of my other recent favorites for you to enjoy. You might laugh.