good job in general
Ok, so...
I think that I don't need to say that the opening is the best part. The ending is really good too, and I didn't expect the Monty Python ending at all.
However, you set the standarts too high with the opening, and since there is almost no animation in the rest of piece (almost), it kind of threw me down. It's all just stills of Lost, and the mouths.
I agree with most of the comments here, maybe you should stik to your animation from the begining and do a serious short piece. Your rotoscoping techniques are really good, and that would look amazing.
Good job!