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Hello everyone,

I'm looking for ways to troubleshoot streaming video issues in Firefox. Sometimes video playback can be affected by browser settings, the internet connection, or device performance.

What steps should I follow to identify the cause and improve playback?

I also came across Selvydia while researching IPTV and streaming services. Would browser troubleshooting differ depending on the streaming platform being used?

Thank you for any practical suggestions.

Hi Mozilla team & community,

I am facing a persistent video playback issue specifically in Firefox (latest build on Windows 11), while the exact same stream plays flawlessly on Google Chrome and VLC media player.

When attempting to stream high-definition HLS live content from my media portal site (https://bidarn.com), the video stalls and buffers every 10–15 seconds. Upon inspecting the Firefox Web Developer Console (Network tab), I notice frequent `NS_ERROR_NET_TIMEOUT` errors during the loading of .ts media chunks, along with occasional CORS flags during concurrent HTTP requests.

I have already completed the following standard troubleshooting steps: 1. Disabled Enhanced Tracking Protection for the domain. 2. Started Firefox in Troubleshoot Mode (Safe Mode) with all extensions turned off. 3. Cleared all cookies, site data, and browser cache. 4. Tested with hardware acceleration toggled ON/OFF.

Unfortunately, the segment fetching latency remains high in Firefox.

Are there specific parameters in `about:config` (such as adjusting `network.http.max-persistent-connections-per-server` or expanding `media.cache_size`) that can optimize how Firefox handles parallel HLS segment fetching?

Any technical guidance or network config recommendations would be greatly appreciated.

Since the last update, I've been experiencing some issues with Firefox on my MacOS. Visiting website such as beatport.com and spotify.com, for exemple, after click on "play", Firefox does not play the sound or video. The same happened with other websites with webplayers.

The problem is on Firefox version 157.0.x (tested on Macbook Air and Mac Mini, same MacOS version).

Title. 156.0 had NVIDIA Video Super Resolution working just fine. 156.0.1 has broken it on my setup. Nothing I have done has brought it back - toggling settings, clearing caches, forcing it on in about:config, etc. The plugin seems to be broken.

Was working just fine for over a year prior.

Latest Stable Firefox 156.0.1 RTX 5080 Driver 596.49 (May '26)

Does not show as working in the Control Panel, and is clearly not working on any video site. YouTube, the BBC, and Twitch were the ones most tested.

Please consider a fix. Thank you.

Okay so this never happened with Chrome, so I'm assuming it's a firefox only issue. Whilst I'm watching a video, if said video is playing in fullscreen, it'll often fade to black during different parts, such as whenever a flash happens or quick cuts (e.g. a film with lightning strikes, causes it to fade to black and it stays like that). It is SUPER annoying and it causes me to have to rewind if I miss something because of it! I don't watch YouTube in fullscreen because of it, but it even does it in streaming services! I honestly have had enough but do not want to switch back to Chrome.

Took this photo of the movie Cruella because I knew there was loads of flashing lights at one scene. You can see that the video is faded but the rest isn't. The second image is when I click multiple times to try and stop it! But it happens again directly after.

And yes, I've tried the 'full-screen-api.transition-duration.enter' and 'leave' in Advanced Preferences.

Playback occasionally lags really hard for 1-2 seconds anytime I watch a video. This goes for all websites, not just youtube. It seems disconnected from buffering as it will happen even when the video is totally loaded. It doesn't lag out any other tabs, and switching to a different tab and back always fixes it (for that moment). I've already tried disabling hardware acceleration and webgl, but nothing changed. It happens about once every minute no matter what. I have a high-end pc, so that shouldn't be the problem. (or maybe it is, and firefox isn't optimized for some bit of hardware that I have) Thank you ^_^

Okay posted this into iOS but never got any proper help, so I'm guessing that was the wrong place to put this.

Whilst I'm watching a video, if said video is playing in fullscreen, it'll often fade to black during different parts, as whenever a flash happens or quick cuts (e.g. a film with lightning strikes, causes it to fade to black and it stays like that - then fades back in super slowly). It is SUPER annoying and it causes me to have to rewind if I miss something because of it (only for it to do it again and again)! I don't watch YouTube in fullscreen because of it, but it even does it in streaming services - but worse! I honestly have had enough of this, it is genuinely infuriating.

I'm on MAC air 2022 M2, macOs Tahoe 26.6.2 - and the most recent up-to-date Firefox update: Version 157.0 I usually put off updating Firefox because it signs me out of everything! Meaning I have to resign into all of my school things, streaming, YouTube, and even this page itself!

Now I've gone into a private window and tested it to see if it does the same thing - yes, yes it does do the same thing, I put on the same two YouTube videos and it did the exact same fading in the middle of it at the same exact timestamp!

Took this photo of the movie Cruella because I knew there was loads of flashing lights at one scene. You can see that the video is faded but the rest isn't. The second image is when I click multiple times to try and stop it! But it happens again directly after.

Please help me, this is really annoying and I've put up with it for too long :(

Hello, I need the player's audio to keep playing while watching a video in the browser—essentially allowing two audio sources to run simultaneously. I have already configured all the necessary audio settings in both the player and the system.

I just upgraded Firefox to version 156.0.2.

It no longer plays mp4 content from a website. It says "No video with supported format and mime type found".

This used to be OK.

My computer just updated Firefox. Since that happened I can't stream a movie in full screen. That is, I can make the window as big as the screen, but I can't hide the tabs, time and date, pull down menu titles, etc, I want to see nothing but the movie. On Netflix you typically do this by clicking on the rectangle in the bottom right corner. But now nothing happens when I click on this. Can you help with this?

Thank you

I uploaded an image to show what I mean, but nothing is showing next to the words Uploaded images.

I'm not sure when it started happening, but whenever I'm watching something full screen, or just full screening, Firefox on Mac, there's this thin white line at the top of the window that's very distracting. Has this been happening to anyone else and does anyone else know how to get rid of it?

All of a sudden all of the videos I watch on YouTube with Firefox are defaulting to mute on my Macbook. I haven't made any changes to settings, etc. I don't have a YouTube account so I can't make any changes there anyway. I am having to unmute each video before I watch it.