How to force YouTube to not use HTML5 player because it is not working on the latest version of Firefox and now I can’t see any video

flash-playerhtml5youtube

This is really annoying. Yesterday everything was working fine, now I wake up only to realize that all the videos on YouTube are using the HTML5 player.

Here is what I see when I try to play a video on YouTube:
enter image description here

I tried what was suggested by the accepted answer in this question, but it didn't work, even after restarting Firefox.

Also I would like to note that YouTube works fine in Chrome (HTML5 player) and Internet Explorer (flash player).

Best Answer

Check if the latest version of Flash is properly installed on your browser. If not, download the latest version and install it.

Then, install the YouTube Flash Player extension:

This add-on forces YouTube to play videos using Flash Player instead of the HTML5 player.