Nearly all video camera housing come with a red filter which is an absolute necessity if/when you are not using video lights.
One thing to remember when using an SLR with video is that your video is going to be ALL blue under about 15'. You will then have to do some serious color correction when you edit the video. The only way around this is to jerry-rig some type of red filter to put on your lens port (of a video/SLR) when you are shooting video, OR, you will need to have BOTH strobes and video lights attached to your housing.
Honestly, the only time that video is interesting (and true) from a video/SLR is when you are your viewers don't care about the color of things - such as video of a bait ball, dolphins playing under water, or shots of a shipwreck.
If you want to get an SLR that also does video, that's fine. But, save the video taking for out-of-the water.