Saw this over at Gizmodo (they got it from Reddit) and figured if I had never heard of it, then the chances were good you guys hadn't either. Apparently there are secret keyboard shortcuts you can use while watching a YouTube video to make it skip ahead.
It's based on percentages, and you simply have to hit pause, and then hit one of the numbers on your keyboard—1 for 10%, 2 for 20%, and so on. Doing so will jump you to the specified section of the video. You can also simply use the arrow keys on your keyboard to move the video forward or back by intervals that also appear to be based on a percentage of the total video length--it's six seconds for some, as much as 20 for longer videos.
The only real caveat is that the video has to be the most recent thing you've clicked on. Assuming that's the case… you can now use your keyboard to quickly scrub through videos to find the section you're looking for.
Apparently this won't work with older browser versions. And strangely, it does not seem to work with the number pad, but only with the proper number keys across the top—for me anyway. I've read some suggestion that it doesn't work properly with full-screen, but haven't had any trouble myself in getting them to work.
The really good news? The arrow key shortcuts even work with embedded videos (though, sadly, the number keys do not work on embeds). Nice.