I think it's good idea at beginning about looping a video, but now there're a number of tool support Youtube auto replay.
Also want to share. I found this Youtube replay tool: http://tubeencore.com. Great interface, useful search feature just like Youtube.
So good to have a few options around.

don't download this, it's broken

Try using http://www.infiniteyoutube.com to loop videos.

In the address bar, add the word "infinite" before the word "youtube". This is the easiest way to put Youtube videos on loop. When you are finished your address bar should be changed from:

http://www.youtube.com/watch?v=dMH0bHeiRNg

To

http://www.infiniteyoutube.com/watch?v=dMH0bHeiRNg

You can also go to http://www.infiniteyoutube.com and just paste in a link to the video or even search for videos.

With the new Youtube layout this script doesn't work at all.

Perfect script.

Simple, two options;
loop selected time and loop entire video.

No fancy bells or whistles, perfect for those who HATE clutter (myself).

Sits very quietly and unobtrusively under the youtube video window.

Though browser add-on scripts add relatively little overhead to overall browser performance (when compared to the things we load nowadays)... the tiny footprint on this script makes it that much more elegant and clean to me.

Thanks for this.

Hey, love your skript, its great if you want to repeat a song or a special part, but adding a button "repeat whole video" would really be great..
best regards

Would be cool if you can have another option "Loop Whole Video" next to "Repeat Selected Time" instead of having to type the whole numbers, I still use it like what it's supposed to do but there are times where I just want the whole video looped, and I don't want to use another script to do that.