One of my friend asked this question on how can he auto repeat youtube video once it has been played to full, but why you would want to repeat a video which you have watched already once. The scenario here is little bit different as it some people listen to prayers, songs uploaded on youtube, so if it your favorite song you may want to listen it again and again while are busy doing other things at that time, so you can manually want to avoid clicking the youtube repeat video button to play the video again.
There are many solutions to this, some of them are web services which allows you to auto replay or auto repeat a youtube video and another way to do this is to install extensions which can help you auto repeat a video on any internet browser like firefox, google chrome or internet explorer.
One such web service is infinite youtube in which you simply need to copy the link to the youtube video, it works like this.
http://www.infiniteyoutube.com/watch?v=dMH0bHeiRNg [ just add infinite to the youtube video URL ]
Other services like Endless Video which we have reviewed earlier can do the same but has more options like number of loops and part loop, some userscripts like this and this can also to the auto repeat in browsers like firefox, google chrome etc. For google chrome, you can also try installing this extension called auto replay for youtube, install from this link and another extension called youturn does the same, install it from this link. If you have any related questions please leave a comment at the end of this post.