There are lots and lots of conspiracy theory videos on Youtube (and I mean a lot of them). These videos can range from being interesting to disturbing on multiple levels (being either because of the content in it, or the kind of conspiracy theory that is being talked about, or the fact that people can believe something so utterly ridiculous) and sometimes these videos end up getting deleted (and even whole pages).
Usually when a conspiracy theorist's video or page gets deleted they'll claim that (insert group here) are the ones whom either deleted the video or their page.
The reality is that this is never really the case, and that in fact there is usually some real, legitimate reasons why conspiracy theorists actually get their videos and pages removed from Youtube:
7. It contains copyrighted materials.
Probably one of the most common reasons why a video (or an entire page) gets removed from Youtube (and not just for conspiracy theorists, but anyone really, including skeptics) is because it contains a certain amount, or a certain type of copyrighted material that does not fall under the fair use laws, and thus is subjected to a DMCA complaint by either a single individual, or an entire group or business.
The recipient of the DMCA complaint does have a chance to get whatever material that was removed restored [example], but more often times then not they won't do this, either because it makes them look like the victim of some dark forces trying to hide the "truth", or out real of fear that if they do so then they might "disappear" after they give out the contact information that Youtube requires to begin the process of whether or not the video or page gets restored.
Of course there are those that say "screw these people, I'm putting that video back up."
6. The video contains hate speech.
Because many conspiracy theories have antisemitic undertones to them (or are blatantly antisemitic) it should be no surprise that some conspiracy theorists are antisemitic themselves, and are bigoted towards other groups as well. It should also come as no surprise that sometimes conspiracy theorists post videos that are blatantly bigoted and targets specific groups of people as well (Jewish people mainly, but other groups such as African Americans and Homosexuals as well) and contains language that can be best described as hate speech.
While hate speech is not actually illegal in the United States (although some kinds is legally questionable) Youtube does have a anti-hate speech policy, and will remove a video if enough complaints are launched (although sometimes this doesn't always happen).
5. The video encourages violence and/or other illegal activity.
Because certain conspiracy theorists believe that the government is preparing to throw certain citizens into concentration camps (or kill them) some conspiracy theorists may create videos encouraging their viewers to violently resist anyone who tries to arrest them. Other times these videos might even encourage the viewers to go out and commit acts of anti-government violence, or show you how to make something illegal, like a bomb.
Other videos might also encourage other types of destructive crimes as well, like vandalism. An example of this would be someone in the anti-GMO movement encouraging people to burn farm fields containing GMO crops.
4. The user is harassing people.
Sometimes when a person is removed from Youtube it has nothing to do with the videos they are posting, but rather it is their behavior and treatment towards others on the site.
While harassing and even threatening people isn't something that just conspiracy theorists do, it is something that conspiracy theorists do sometimes do in order to try to scare a skeptic away from Youtube. Sometimes it works, most of the time it just gets them in trouble with Youtube (and law enforcement).
3. The videos contain graphic images.
Sometimes Youtube takes down a video not because it's actually encouraging violence, or has had a DMCA complaint was launched against it. No, sometimes it's because the content in the video was simply to graphic to be allowed on Youtube, even under an age restriction.
2. They get hacked.
Many times when a conspiracy theorist's page on Youtube goes down they'll claim that their page got hacked by the government, and sometimes they are right (at least about the hacked part, not about the government part).
The truth is that conspiracy theorists do sometimes end up angering the wrong person, and said person might feel that Youtube is taking to long to take down a video or someones page (or they don't even bother to try to let Youtube handle it) and if they have enough skills and know how, they hack the page and get rid of whatever they don't like (an action in which I neither encourage nor endorse).
1. The user does it themselves.
Sometimes conspiracy theorists actually take down their own videos and then claim that Youtube told them to take the videos down, which Youtube does not do (Youtube would just take down the videos and then send a warning).
While there are probably multiple reasons why a conspiracy theorist takes down their own video, the most likely reason is that they want you to think that the government has something to hide, and thus it gets their own page more attention from other conspiracy theorists.