For the Canon DSLR I think he meant the Rebel T1i which shoots HD video.
A useful site for tech comparisons is : http://www.dpreview.com/ or http://www.steves-digicams.com/
Since you have lenses its very hard to beat the features and quality of the DSLR shooting through good large glass (or plastic as most are now) for stills. Would also give you a lot of options for composing video. I have not shot video yet w/ a Canon DSLR so I can't comment on image stabilization which would be a must for our application.
Go to the shops and try them all, test the image stabilization and if buying a small camera to do video check the ability to zoom while shooting video, many can't do it optically, they do it digitaly which isn't the best quality. The dpreivew site did a review of waterproof cameras last year. Don't recall if any had image stabilization but they could shoot 720p video at 30fps.
Happy hunting.