works and has a toolbar, unlike James fray's YouTube™ No Buffer (Stop Auto-playing), but for some reason the devs Allen and Mark think this tool needs to reload all currently open tabs. very annoying hence unusable hence one star. sry

if at least the reloading wouldn't refresh the history, but it does.

Ha-ha!!! It reloaded all and every youtube tabs at once and started all videos simultaneously!
Whatever button developers proposes me to choose - play/pause/stop, the result is the same: all streams noise at the same time!
How stupid!

Not working for me in 54.0.1 (64-bit) on Mac. No pause. No stop. Just plays all videos immediately. Plus, when I click to advance the video playing location it jumps back to the beginning of the video. Obviously, this add-on is A WASTE OF TIME.

It will stop the first tab I open in the background, but it won't stop any others. since the whole point is to pause YouTube videos when you open them in a new tab so you can keep looking after you open a video, only pausing one video defeats the purpose. The problem can't be on my end since I just reinstalled Firefox.

The point for me, and I imagine many others, is to stop the video from playing automatically when you open a Youtube page that hosts a video. To have the audio playing and the video stopped does not solve the problem! If one is at work or simply doesn't want to waste the time of having the video load and play, or doesn't want to hear it... all these pruposes are not served by this plugin.