Unable to play youtube videos in Ubuntu 16.04

[robbyx]

The videos appear to start but instead I see a black screen with:

"No video with supported format and mime type found"

I have installed the addon HMTL5 video everywhere but it has not made any difference.

What should I do next?

[James]

Not sure what specific packages you need with Ubuntu but you need say FFmpeg as Gstreamers has not been used for quite some time now.

You can use https://www.youtube.com/html5/ as all checkmarks should be blue if you have all necessary packages installed for the HTML5 player to work.

[robbyx]

Thank you. All the checkmarks are in blue.

I seem to have found the answer. It is that I should disable youtube playbacks in the HTML5 everywhere's options. Why I do not know, but I have the videos playing! Any Idea why?

BTW HTML5 anywhere is not putting an icon in a toolbar. I have had other addons fail to do the same. In the past I would find all the missing icons under customise. Where do I find them in FF 56 64bit?

[robbyx]

I checked your idea of ffmpeg and found that it was not installed as per synaptic. I therefore installed it and now I can remove the tick against youtube in HTML5 everywhere. So I assume that not applying html5 in youtube defaulted to the non html5 driver. Thank you.

If you could comment on the missing icon I would be grateful.

[robbyx]

Today i started the computer and tried to run a youtube video. The same error message stopped the playback ie "No video with supported format and mime type found"

I unticked the box for youtube in html5 everywhere and the videos played. Do you know why I had to untick the box?

[Grumpus]

In /edit/preferences - Have you enabled Digital Rights Management (DRM) - Play DRM controlled content?
It does seem to help.
You might also look in about:config for plugin.load_flash_only - right click and toggle it to false and see what happens. Other plugins will become visible in /tools/addons/plugins.
Make note of any changes and you can toggle it back if it does not help.
Do you have any media related extensions added to Firefox?

[robbyx]

In /edit/preferences - Have you enabled Digital Rights Management (DRM) - Play DRM controlled content?
It does seem to help.

On Gnome 16.04 it made no difference.

You might also look in about:config for plugin.load_flash_only - right click and toggle it to false and see what happens.

That plugin line is not in my about:config[/quote]

Other plugins will become visible in /tools/addons/plugins.
Make note of any changes and you can toggle it back if it does not help.
Do you have any media related extensions added to Firefox?

Here is my list of installed extensions. I have not been able to find which one, if any, would be causing my problem with youtube playback. Would you mind looking over the list for any candidates for the cause?

Application: Firefox 56.0 (20171003101344)
Operating System: Linux (x86_64-gcc3)

- Activity Stream
- adaware ad block
- Add Bookmark Here ² (Disabled, Incompatible)
- Application Update Service Helper
- Click-to-Play staged rollout
- DuckDuckGo Plus
- Enhancer for YouTube™
- Extension List Dumper 2
- Firefox Screenshots
- FlareGet Integration
- Flashblock
- FlashGot
- Follow-on Search Telemetry
- Form Autofill
- GNOME Shell integration
- HTML5 Video Everywhere
- LastPass: Free Password Manager
- Multi-process staged rollout
- Nimbus Screen Capture
- NoScript
- Page Colors & Fonts Buttons
- Photon onboarding
- Pocket
- Popup Blocker Ultimate
- PubMed Links Enhancer
- Qwant for Firefox
- S3.Google Translator
- Safe Browsing Version 4 (temporary add-on) (Disabled)
- Shield Recipe Client
- Show Password
- StumbleUpon
- Stylish
- Tampermonkey (Disabled)
- Theme Font & Size Changer
- uBlock Origin
- Ubuntu Modifications
- Uppity
- Video Downloader professional
- Video DownloadHelper
- Vimeo Free Downloader
- Web Compat
- WorldBrain - The (Re)search-Engine
- Xmarks

[dickvl]

Maybe try a new clean test profile.
http://kb.mozillazine.org/Standard_diag ... ile_issues

If the new profile works then you can transfer files to the new profile.
http://kb.mozillazine.org/Transferring_ ... _-_Firefox