Unfortunately the ideas one may have about video content for YouTube may consist of content which would render the video ineligible for earning income with - Content including video game/software footage, favorite music and video scenes.
These restrictions are what some would call unfair. On one hand people are encouraged to 'share' YouTube content on popular online networks such as Facebook, Twitter, Blogger etc promoting things like songs and movie/video game trailers...on the other hand, individuals don't have the rights to "use" the content to liven up their own videos.
One can 'favorite' items, subscribe, comment on videos, link to, 'share' and so on...but to include any content that isn't yours, and making money from it is out of the question.
As an individual, what chances would one person have in gaining permission from a major copyright holder to use their material in order to make a few extra dollars on the side? Extra dollars earned online, with the proceeds spent on internet access.
Apparently recording software (i.e. A video demonstrating what Apple iOS 5 is capable of/how it works/what it looks like) is deemed more 'commercial' than educational and it is not permissible where one intends to generate income from the video (yet some people pay for private education all the time).
You'd hate to think that people that create good video content will stop because what they can and cannot do is controlled to the point where it's not worth the trouble in trying to do something good both for themselves, as well as for others.