This inspired me to poke around on YouTube. To my surprise, I found that they actually provide three stills from each movie, with predictable URLs (thumbnail URLs end with
/2.jpg; the other frames are
/3.jpg). However, YouTube only displays a single still, as the thumbnail.
So I wrote a Greasemonkey script that flips thumbnails between all three images at very short intervals, essentially animating them: YouTube thumbnail animator.
Now, this isn't really the scannable sequential imagery of the Signal vs. Noise post, but it's still cool and rather useful. Perhaps a bit CPU-greedy.