Problem playing HTML5 videos

[nownthen]

I have a problem playing Html5 videos in Google Chrome and also in EDGE, it also happens once in a while in YouTube also. Sometimes they open and play perfectly but other times they show a blackish screen with the message:

‘Your browser does not currently recognize any of the video formats available'
Click here to visit our frequently asked questions about HTML5 video’

I have clicked on the message but not sure what to do.
How do I resolve this problem?

 

[Bighorn]

There's no clickable link to one of the problem videos and no mention of the format of the videos to check for the issue/s but I don't have trouble with YouTube videos, use Ant.com browser helper to download them and VLC to play them later. VLC can play the formats I see such as .mkv, .webm and .mp4 among several others.

 

[Wolfie]

Try FireFox browser and see if you get the same issue, if you don't, it may be a codec problem?.

https://www.mozilla.org/en-US/firefox/new/

 

[Ian]

Do you have any addons in your browser that could interfere with video playback? If you have anything video/download related in browser addons, I'd try temporarily disabling them.

edit: If you are using an ad-blocker, try disabling that too and see if they then start working.