I have just installed Lubuntu 14.04.

I can run .mp4 video files directly with Firefox but if i put them into an HTML5 tag then I get error: 'video format or mime type is not supported'.

I have been searching for a solution to this for hours now, I've tried so much but to no avail.

I am using Firefox version 28.0.
OS: LUbuntu 14.04 and I have:

• Installed flashplugin-installer.
  


• Set media.gstreamer.enabled to false in about:config.
  



• Changed the .htaccess file to include:
  

  
  
  

  AddType video/mp4 mp4 m4v f4v f4p
  
  AddType video/ogg ogv
  
  AddType video/webm webm
  
  AddType video/x-flv flv

And I have also done:

sudo add-apt-repository ppa:mc3man/trusty-media

sudo apt-get update

sudo apt-get install gstreamer0.10-ffmpeg

According to: 10 Things To Do After Installing Ubuntu 14.04 Trusty Tahr To Get A Near Perfect Desktop

Then I installed Lubuntu extras, as is detailed here, but its all to no avail and the error just persists.

Does anybody know how I can get to view HTML5 embedded .mp4 files in Firefox?