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After upgrading to Firefox 34, Flash videos stopped working. A black screen was presented, with no hint to the problem. Following these instructions and these other instructions, would prove futile.

Setting YouTube to playback using HTML5 also did not resolve the problem.

Community
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Dave Jarvis
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3 Answers3

9

The Flashblock add-on is incompatible with Firefox 34; remove the add-on.

The following might work (untested):

  1. Start Firefox and press Alt+h to open the Help menu
  2. Press t to select Troubleshooting Information
  3. Click the button for Open Containing Folder (or Open Directory)
  4. Create a folder (directory) named Chrome
  5. Create a new file named userContent.css
  6. Copy the following text into the new file:
    /* Flash Block */
@namespace url(http://www.w3.org/1999/xhtml);
@-moz-document domain("youtube.com"){
#theater-background { display:none !important;}
}
  7. Save and close the file
  8. Restart Firefox
Dave Jarvis
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1

Solved for me : I just removed the "Adobe flash player" installed through the Ubuntu software center. It may conflict with the firefox flash plugin Firefox and chromium OK

seba
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0

Since Adobe flash plugin 11, there are no adobe flash updates available for firefox in linux. So sites like youtube & others asks to update the flash plugin or simply unable to play the videos showing black screen because of out-dated flash plugin. Try this link i find it useful and worked for me. http://www.webupd8.org/2014/05/install-fresh-player-plugin-in-ubuntu.html

Sudheer
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