I don't know whether its a new feature or old, but you can scrub through videos in the latest version of the VLC media player by double finger scrolling (in the left or right direction) on the trackpad of newer Mac laptops.
[robg adds: This is definitely new in 0.9.2; I have both it and 0.8.6, and there's no scrubbing via scroll in 0.8.6. You can also scrub with a Mighty Mouse, and with any mouse capable of horizontal scrolling -- which should be any mouse with a scroll wheel. You just need to hold Shift while using the scroll wheel to scroll horizontally while using such rodents.]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20080921130758424