This video clip focuses mainly on the crab spider that lives in pitcher plants, but it briefly shows a tadpole and some sort of crab at the end. Kinda cool. ~23 Mb
This video is from Episode 8 of the TV series "Planet Earth" - 'Jungles'. If you have problems playing the video, try VLC video player, which runs just about any type of video out there. This is currently hosted on Rapidshare as a free user, so the file link will expire after some time.