I've tried to restart the browser, but it doesn't seem to fix the problem. I've sent a feedback via SlimJet a few weeks ago but never heard anything back.
Hope I can get an answer or, a solution to this problem.

I still have the latest Firefox installed and updated, even though I like Slimjet a lot more. So I guess that I shall do the same thing.paul1149 wrote:My other Chromium browser, Vivaldi, does this as well. It is a frequent problem, and getting worse. I now use Firefox to access twitter for this reason.
And this:But do you use the official build ("dev-official") or others, in your chrlauncher.ini file? With "ChromiumType=dev-official", MP4 videos do not work natively. Change to "ChromiumType=stable-codecs-sync" for example. Update. -https://www.reddit.com/r/Chromium/comme ... t_support/
Hello. This is because Twitter uses proprietary codecs in video files. Info at https://support.twitter.com/articles/20172128 (search the "mp4" word in this page). By default, Chromium does not support proprietary codecs (AAC, MP3, H.264/MP4) https://www.chromium.org/audio-video in the HTML <audio> and <video> elements. So, Chromium cannot natively play proprietary codecs :/ The only way is to compile Chromium yourself from its source-code with enabled proprietary codecs... or use another Chromium-like browser. For info, on Windows OS, we recompile Chromium with proprietary codecs (check guides at http://chromium.woolyss.com/#source-code) So, I well know this issue!-https://www.reddit.com/r/Chromium/comme ... t_support/
"why Chromium does not support H.264/MP4" Because it does not support proprietary codecs. Only free and open-source codecs are used. Note OpenH264 exists and is supported by Firefox... but Chromium does not use it :/ If you are developer, you can build your own Chromium version with proprietary codecs enabled: GYP_DEFINES proprietary_codecs=1 https://chromium.googlesource.com/chrom ... uctions.md -https://www.reddit.com/r/Chromium/comme ... ost_video/