MariMite definitely has the potential to be source for many comical concepts in AMVs. Already there are a few out there.
Most of my favorite MariMite comedy vids are... not for the faint of heart. It is important to note that the humor value is derived from the absurdity of combining the video and audio sources. Indeed, it is the dichotomy between the peaceful ("walking slow is preferred here") feeling of the show and the shock offensiveness of the audio sources that make the videos funny.
Both of my examples for this particular type of of video use foul language, so be aware of that.A good example is Kai Stromler's
As Charged. It is best described by this part of the official video notes:
Or my own
100 Dollar Bill which definitely does the "lip sync is cruise control for comedy" routine.
Hint: the joke they're discussing is from Chasing Amy, and is about who out of of Santa Claus, the Easter Bunny, a male friendly lesbian, and a "man-hating [not nice term for a lesbian]" will reach a 100 dollar bill placed equally distant from each of them first.
(Disclaimer: I do not advocate slurs against homosexuals, clearly, but it is in the audio source. I also believe my video was the reason for my invite to the forum, so I'm pretty sure it's acceptable to post. If the mods disagree, they can remove it. I won't feel slighted.).