Progressive, HD. I like my video in the highest quality I can get it. Streaming can be problematic for me as my internet has a tendency to cut out unexpectedly.
Sometimes I'll download videos to throw on a device so I can watch a bit before I sleep (bombin' in bed) but usually I just use Progressive HD. If I have a game open or for whatever reason need my CPU for something I'll use HTML5, since flash destroys my cpu a lot more than html5 does.