It's wonderful, but there is a few small bugs:

1) It starts playing some hidden video on channel pages and some video listings (can not be stopped)
2) It does not work with clips (prevents playback)
3) It does not work with videos that have content warning (prevents playback), an example video: https://www.youtube.com/watch?v=9vz06QO3UkQ

I have the settings 1, 3 and 4 enabled.

Since 16 sept 2021 does not work.
(FF86)

The extension works great. However, there seems to be a minor bug that prevents me from posting a comment on YouTube videos. I can only post comments when the extension is disabled. Other than that, I'm loving it!

Nice for autostopping videos when playing a playlist, but I'm not seeing the big red play button on top of the video?

conflict with you tube ADULT VIDEOS

WORKS 8 SEPT 2018
I WOULD LIKE A BUTTON TO DISABLE IT ON THE TOOLBAR

pratique, rapide et belle présentation!

Finally found an add-on that can disable auto-play in playlists. Just go to preferences from the add-on page and select 'Stop auto-buffering the player on play-list mode'

To prevent it from playing a few seconds of video, you can go to about:config and set "media.autoplay.enabled" to false. This prevents unwatched videos from showing up in your watch history. However, it technically still buffers for a couple seconds before refreshing. This firefox setting does not prevent auto-play in playlists, which is why I downloaded this plugin.

currently, this one work well on Youtube

Nice

Good

Does the job