There was no science to it at all, although I was hitting the button quicker when I knew there was a good shot coming up, I didn't pause or frame advance or anything. I've got 5989 caps saved to a CD right now and they're actually pretty clear (for the most part - there are some dodgy ones in there as well)
Would anyone be interested in me setting up a gallery with them so you can use them as well? (If I do make a gallery I'll edit out the crap ones! Hell, I might even link it into [ chalk it up to hormones ] (the Bewitched, Bothered & Bewildered screencap site I run) Here's a couple of sample caps so you can see what the quality's like (haven't touched these at all - no sharpening, brightening, nothing)
Okay, I really hate the Rich Text Editor on LJ!!! Gah!