Hi, is that the only site where videos don't play?

Any possibility that it is blocked by the Enhanced Tracking Protection feature? Its shield icon toward the left end of the address bar usually turns a bit purplish when content is blocked. Click the icon to learn more or make an exception. See: Enhanced Tracking Protection in Firefox for desktop.

More generally, I have a copy of Google's old video code support page up that you can use to verify broad codec support in case there is an issue there: https://www.jeffersonscher.com/sumo/html5-video.html

Thanks for the suggestion but that was the first thing I tried. The problem persists even in Firefox version 86. I have tried refreshing Firefox, running it in safe mode, and disabling my firewall/antivirus.

Thank you, and on the other two points:

• Is that the only site where videos don't play?
• I have a copy of Google's old video code support page up that you can use to verify broad codec support in case there is an issue there: https://www.jeffersonscher.com/sumo/html5-video.html

Yes, it appears to be just with this Sinclair Broadcasting station. The videos run just fine using Edge.

One other thing you could check for would be error messages in Firefox's Web Console. You can open the Web Console in the lower part of the tab using either:

• "3-bar" menu button > Web Developer > Web Console
• (menu bar) Tools > Web Developer > Web Console
• (Windows) Ctrl+Shift+k

Click the little trash can at the upper left of the list and then reload the page in the upper part of the tab and watch for new messages. Anything that sounds like it could be relevant -- blocked URL, unsupported codec, that sort of thing?

Just got off the phone with Sinclair Broadcasting the owner of the station. When Sinclair attempted to view the same video on their website KOMO.com using Firefox they had the same problem I have and were unable to view the video, both them and I have no problem when using Chrome or Edge. The problem is with Firefox

Loading failed for the <script> with source “https://rum-static.pingdom.net/prum.min.js”. komonews.com:1:1 Loading failed for the <script> with source “https://tagan.adlightning.com/sinclair/op.js”. komonews.com:272:1 Auth0 client for: komonews 2 presentations-home_v1.min.js:1:799650 Some cookies are misusing the recommended “SameSite“ attribute 5 Filter(s) 'top_videos_teaser' did not return data. presentations-home_v1.min.js:1:329644 Filter(s) 'premium_content_teaser' did not return data. presentations-home_v1.min.js:1:329644 Auth0 client for: komonews presentations-home_v1.min.js:1:799650 Auth0 client for: komonews presentations-home_v1.min.js:1:799650 Loading for: https://komonews.com widget.js:1:519 Loading failed for the <script> with source “https://ads.rubiconproject.com/prebid/21162_KMPH_KRNV_Sinclair_DM.js”. komonews.com:1:1 Use of the orientation sensor is deprecated. user.js:147:271 This page uses the non standard property “zoom”. Consider using calc() in the relevant property values, or using “transform” along with “transform-origin: 0 0”. komonews.com Request to access cookie or storage on “<URL>” was blocked because it came from a tracker and content blocking is enabled. 2 Uncaught (in promise) TypeError: query[q].split is not a function

   parseQueryString https://komonews.com/resources/video/players/prod/src/scripts/jwplayer/player.js?_=2021-02-19T00-21Z:128
   configureProps https://komonews.com/resources/video/players/prod/src/scripts/jwplayer/player.js?_=2021-02-19T00-21Z:48

player.js:128:30

The last one is suspicious:

Uncaught (in promise) TypeError: query[q].split is not a function player.js:128:30