Tried it, does not work consistently. Even if it did work consistently, it does not give any indication that the video was added to the queue, and as far as I know, it only works for the page where it is used. I could be wrong, there is nothing else except that button; no list of videos, no way to remove videos, or change their order.

Works as expected! Easy to use, and definitely the must have while working/partying
Feature requests:
1. It would be good if I'm allowed to put multiple videos in the queue with the set priorities.
2. Disable 'play next' option

Very useful feature.