Firefox Community Forum

Windows 11 Pro - Dell XPS8940 desktop - i9

Firefox will not play video from a website. If I save the video, it is a MP4 file. Windows Media Player and VLC will play the video file. But the browser shows the message: "No video with supported format and MIME type found."

Chrome and Edge will play this video correctly in their browsers. Firefox will not play the video on 3 different computers, and even when a different user account is involved (without Firefox sync).

The evidence seems to point at firefox. The website is a Wordpress site.

Is it possible that the website is the problem? If so, why do Edge and Chrome work?

I uninstalled Firefox (latest version) and reinstalled it. Not fixed.

My windows updates are current, as are Dell updates.

This is stumping me. I hope someone can help.

Some videos on X don't play. They show the continuous circle loading. Copy that video link and load in private browser and it plays normally. How do I find out what is keeping them from playing in the normal browser. I tried disabling all extensions. No change. Any ideas I can try?

Hello Team, I am having issues with Mozilla Firefox and Nightly Browser sound. If I use another browser, the sound is perfect. I have been using Firefox for years now and am accustomed to it, as well as Nighty, for all browsing needs.

Regards, Roopesh

I´m currently working on some courses in Udemy and all of a sudden the videos are not loading, is not my internet connection I deactivated all the extension to see if it was the case but nothing seems to be working

Good morning from germany,

I am a multiple year subscriber and wanted to watch game 6 before going to work (it is around 6 am over here) but the player isn´t running and it states that games can not be played, even the recap doesn´t start. Other videos are running as on youtube and other social networks. I switched a VPN from location germany to location USA to off but nothing works. I am using the newest version of mozilla firefox.

Can you give me some help what I can watch in order to watch the last two Finals games as well?

Thx guys

I have noticed recently that when i try to play certain videos i am sent that are embedded on webpages the screen just goes black and i cannot see anything but i can still hear the video playing in the background. Why is this happening. I have a new HP envy laptop and am using firefox browser but when i use my work laptop which does not have firefox (IBM Thinkpad) i do not face this issue therefore i assume it is a setting in firefox

Each time a video call comes in, the message on messenger, says Video calling is not supported on this browser. I've gone to the browser settings and cannot find anything that would change this. Help.

Hi,

I have been having this weird issue that I believe is being caused by firefox as no other internet browser has the same issue. When I'm playing music on spotify and I open firefox the sound goes quite bu the audio is still playing on spotify . One work around I have found is to take on of the tabs and use it to open a new window and the put it back with the others and the sound comes back again. I lost and need help as this is making it hard to want to use firefox which I have been a user of since it first came out.

Hello. On/about 25jun2025 the sound on my Firefox videos stopped working from any source. I know enough to determine the problem is on Firefox. Videos on MS Edge worked fine. Sound works form VLC songs, etc. Sound does work with earplugs. Wondering if that could have caused the loss of speaker sounds. You think I could delete my current firefox and reinstall it. That would be a pain (an hour or so to set it up again.) Thanks, Bill

I went to cp24.com and the video on the right side should load the news channel live automatically but it won't load, I tried downloading a new extension but still does not work, any help would be great, thanks!

After opening a YouTube page and selecting a video to watch, I get a second page with the word DOWNLOADING on it. Sometimes is just another blank page that goes away almost immediately. This happen often.

Using iOS on Mac Mini desktop, I get no sound on democracynow.org but on the iPhone the sound works fine. Most other streams/videos have fine sound but not imdb.com on the desktop with iOS but again, fine on the iPhone.