Sadly it does nothing - simply does not work.

No longer functional with new YouTube design

doesn't do what it should do. doesn't show what should this show.

No longer works. Icon appears in browser. Click to get slider and does not show.

Please, update this!

No slider whatsoever.

Does not work. Just garbage.

don't work, no slider appears

Does not work, no slider!!!!

Thank you to mikeloeven for the idea.
Use this link to get the old youtube format: https://www.reddit.com/r/firefox/comments/74j8r6/how_to_set_old_youtube_layout_permanently_in/

It should work after, make sure to reload.

The main problem with this addon appears to be the youtube material layout. I suspect the plugin does work but as the last update was 2016 it has clearly not been updated to work with you tubes new material design layout. a simple layout update by the author should resolve the issue and restore full functionality to the addon

dont install. doesnt work! no slider, nothing

just doesn't work. Icon appears on install but doesn't do anything. No slider appears,

Clicking the tool button does nothing besides delay the audio even more than usual... zero useful functionality.

No slider! No control. Non functional!!
Waste of time?
Perhaps some directions might be useful... just in case there was actually some point to this 'tool'.

Does not work. Not in Firefox, not in Chrome

I like the idea but it doesn't seem to work for me. I click on the activate button and nothing happens. Do I need to re-start FF 57 for it to work?

Plugin is amazing, however I have a plugin called "Enhancer for Youtube" that allows me to play videos in Cinema Mode, and when everything gets darked, the Audio Sync stays on top of the page and it doesn't get darker too.

As the title says it seems to work most of the time; the slider doesn't always appear when I press the "activate" button. When it does appear it seems to do what it is supposed to do. One thing it doesn't warn you about is that you no longer have volume control.
This is functionality that should really be built into the Windows sound manager since it has been known for years that Windows Bluetooth has lag problems.

Doesn't seem to work for streaming...I like the slider and idea though.