I have a 1D Mark IV with a 24-70 F2.8L. I love the video quality of it but using it like a video camera is just impossible.
FIrst of all, it's too heavy and bulky. Moving the focusing ring sucks. The screen is not moveable so you have to keep your eyes on the display and that means keeping the camera away from your body, which creates more instability. When the image is out of focus, it's hard to figure out which way to move the focusing ring. Sometimes, you get lucky and it focuses, but if you go the other way, there will be a couple of seconds of out of focus video.
I don't understand the big problem.1920x1080 Full HD video is only about 2MP. On a 16MP sensor, only a portion of it is used for video.
My camera can take 10fps. That's just a third of 30fps and at full 16MP. Why can't the camera use just the part of the sensor for video and the rest for the AF in servo mode at 30fps?
I don't know how video cameras do it. i have a $300 Panasonic SX1 Full HD camcorder with an 8GB SD Card. This thing has the fastest focusing i've ever seen. It focuses from macro (about 1/2") to infinity without even blinking. The quality is AVCHD. More than enough for most but of course, it doesn't compare to the Canon and a good F2.8 lens. I think they already know what to do with VDSLR AF, but releasing a camera that will basically kill professional camcorders probably won't happen any time soon.
I bet the people at RED and such are super pissed off at the 5D II and all the money film makers are saving with cameras like it.