Make an HDR video was one of my dreams, I always wondered how to make it work, until today. With the newest update of the Magic Lantern software for Canon cameras is now possible very easily and cheap!
Below I show my fist attempt of doing this technique.

I used a Canon 600D (T3i) on 720p 60fps video mode. Magic Lantern does shoot one overexposed frame and on underexposed frame, giving an output of a blinking video.

To make it work you will need a post processing software such as After Effects or Nuke to extract every odd and even frames and blend them together with a luma key applied as a mask to key out the overbloom areas and have there the information in the underexposed sequence.

Below I show you the both frames and the final result.