The alst ones were pre-recorded. I think the protocol was to record it, upload it to YouTube, and the winner was picked from tharr. Someone like Echaose would know better. I haven't taken part in any of the previous ones (I wanted to, but I was unavailable at the time ).
Pretty much your standard lip synching, yep. Then I guess the GFers vote for the one they like the most. It doesn't have to be the most talented lip synching, it could be funny or serious or whatever. (I know I'll be going for the funny aspect. XD)