Make sure you are not blocking content.

Start Firefox in Safe Mode {web link}

A small dialog should appear. Click Start In Safe Mode (not Refresh). Is the problem still there?

One issue that seems more common lately is Firefox's Tracking Protection feature. When it is blocking content in a page, a shield icon will appear at the left end of the address bar next to the padlock icon. This article has more info on managing this feature: Tracking Protection {web link}

Thank you very much for the reply!

I induced safe mode, the video reappeared and played just fine. Now i did a troubleshoot on extensions, themes and hardware acceleration, which deleted my adblocker. Is there a solution to this ? aka have an efficient adblocker and still not get blocked out these videos? Thank you.

Dis the blocker on that website. Is the problem gone?

kecskesadam said

I did a Troubleshoot on Extensions, Themes and Hardware Acceleration, which deleted my adblocker.

Is there a solution to this? That is, have an efficient adblocker and still not get blocked out these videos?

List all your Extensions, Active or Inactive.

What Ad Blocker did you have? I have uBlock Origin which for me is more Memory-Friendlier than AdBlock Plus (ABP). Usually, it's the Content Blocking settings of Cookies that will mess-up some Website function, such as videos, images, button-clicking, etc.

Also, stacking Extensions which do similar or the same functions, should not be done. Such as, running two or more Script-Blocking Extensions.

The greater quantity of Extensions, the more likely problems like conflicts - slow-downs - hang-ups - freezes - etc.

Do you have a public link to your video-problem site?

Also, FF has a newer AutoPlay Block Feature. Check its setting.

~Pj