What are the best Flash video frame dimensions?

As part of the changes we've been making to the video encoding on our Web site, we've been looking at a bunch of movies that people have uploaded, and wondering why some come out better than others.

One thing that makes a huge difference is the resolution of the source video. There's one really simple rule to remember: video codecs perform best when the frame width and height use multiples of 16. So 768x432 will actually look better than 896x504, even though it has fewer pixels.

Here's a handy guide to the best video resolutions for both 4:3 and 16:9 videos, courtesy of encoding.com.