This route outputs raw HD via HDMI. The Matrox device will capture that HDMI and pass it onto your video capturing software. The software will then encode that into a video file. What format? Any format that your capturing software can produce. In Final Cut (or iMovie), it will be any compression standard that can be wrapped into QuickTime (i.e. MPEG-4, MPEG-2, CineForm etc). I'm not quite sure what are the options in Windows, but I'm sure anything that can be wrapped in an AVI or WMV container will be fine.

So, what this gives you is:

1. Immediate availability of low-compression HD files for reviewing and editing;
2. Better chroma space (4:2:2, rather than 4:2:0 that you get from AVCHD);
3. The ability to edit on a less-than-fastest computer

YouTube has plenty of videos about Matrox MXO2 Mini device. While most of them are on MacBook Pros, I believe some show Windows laptops.