My Coby mp610-2G mp3 player won't play videos?

I have a mp3 player from Coby- a mp610-2G. Well, I have a video put on it- one of those snagged from Youtube ones. I can't play it. When I click on the Movie option when using it, it tells me there are no files. However, when I go into Explorer on my mp3 player, it shows the file. I click on it, and it sends me back to the Explorer option. I can play the movie on my computer, and it shows up in the Movie folder i have on the computer, but for some reason I can't get any videos to play on my mp3 player. Any idea of why?