A simple hint for the new Quicktime X player. Clicking the fast forward button increases video playback speed to 2x, then 4x then 8x. 2x, however, is a bit fast to watch a video.
To increment by .1x, hold down Option and click fast forward. I find 1.3x speed works well, and is very watchable. This also works for reverse.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20090909210410453