Works, definitely works.
Without this little addon listening to music on youtube for extended periods of time would be an absolute nightmare.
However, does have some small problems.

1. Sometimes doesn't work for whatever reason, rarely though.
2. While it does stop youtube confirmation popup from bothering you every 5 seconds, it does not put the video on loop, so after a while the video will stop playing (since youtube's integrated loop function only loops for a couple of times at most and then stops.) Therefore i wish this addon could also click on the 'play' button automatically whenever it detects that the playback had stopped. That'd be great.