A Youtube URL goes in the big box.
You may optionally define a start and/or end timestamp in the smaller box.

Examples:
01:30
   • End at 1min 30sec.
00:20-
   • Start* at 20sec.
00:30-00:50
   • Start at 30sec and end at 50sec.
-00:05
   • End 5sec before end of video.
00:30.5
   • Seconds may be fractional.


GreaseMonkey:
Here is a GreaseMonkey script that will add "Great Job!" links on Youtube pages. (Updated: 04.16.08 v0.2.8)

• This site is by W.T. Snacks.


* Due to the limitations of FLV video, the video will start at the preceding keyframe.