In order for the use of a copyrighted work to be "fair use" it has to qualify under a 4 part test: (1) purpose and character of the use & whether it is commerical or nonprofit; (2) nature of the work; (3) amount of the portion of the work used in relation to the copyrighted work as a whole; and (4) effect of the use on the potential market for the vlue of the work. So, what you may think in your mind is fair use may not be so in the mind of the copyright owner, nor of the court.
Fair use is a defense to infringement. That means you usually get sued first and then raise it. It'll cost you $10,000 to get out of the lawsuit
If you are running ads that are showing the vids, etc. that would be de facto commercial use in my mind.
Go to talk to a lawyer and show him or her what you plan on doing. Be specific as that's going to impact on the ultimate answer. Good luck.