Quite a few people have emailed/PMed me regarding this phenomena of merging genres of ViDSLR or DSLRideo (sorry I've been busy and can't come up with a snappy new term yet) and how big it's going to get (Also why is it you guys can't post a question here instead of contacting me? You get quicker service out here
). I have to say right now it is in its infancy. The H264 codec looks pretty darn good at 39mb/s (4.8 MB/s). It's more film like than HDV or even the XDCAM EX and the color looks comparable to 1080i DVCPRO HD. For B camera broadcast, I doubt any one would say no. Principle capture? Well, the engineers in broadcast have pretty stringent and strange criteria for codecs, and they can't seem to separate acquisition codec from editing/delivery codec.
Right now, the best offering is in the Canon 5DmkII. The best in the sense that it is available with interchangeable lenses and that a plethora of DSLR housing manufacturers will be covering this model. They have the port systems to work with pretty much every lens useable u/w. There is very little that is known about the way the 5D shoots video in terms of modes available. Shutter is auto between 1/30 to 1/125. I can't find anyone who's handled the camera to say how to control exposure except via AV mode. Apparently manual aperture control is possible. but with a small range of shutter speeds, it's more a club than a scalpel. For underwater, the lens choice will be an awesome boon with 1:1 easily available as are FE and rectilinear WA lens. The problem I'm guessing are the length of recording (4GB file limit), battery life and for the housing manufacturers, stability. Shooting a still is easy so handling has never been as crucial to DSLR housing makers. Many just add float devices to keep the housing from being too negatively buoyant. However, with video, handling is doubling crucial for a steady picture. Notice all the demo vids from canon are all locked down tripod shoots?
I'm trying to get my hands on the camera soon and will report more but it seems to be adequate for run n' gun shooting that a news journalist on location in a war zone or something. The verdict is still out on its usefulness underwater.