My internet is presently sucking quite hard, so I tried only two videos. One, a Frozen parody of some kind took a long time to not work (with an on-screen error message of "Video not found or access denied"). The second video, something on the front page called "Obj. 36 Laws of Sines and Cosines", worked fine.
edit: for the hell of it I tried another, "I Have A Dream Speech Short Version". Took a long time "Waiting for...", then "Connecting...", then, blammo, worked fine.