Can't watch any videos- file not found

EDIT: If you are using the add-on HTTPS Everywhere in Firefox, it will cause this problem.

Every time I try to load up a video, no matter what it is, I get the same error that the file wasn't found.

I'm using Ubuntu 13.10, Firefox 26.0. I've included a screenshot of the error message.

Is this just recently happening? Do you have any other browsers to try other than firefox? Testing with FF 26 on a Mac I'm not having the same problem. 

I last tried to watch a video a few days ago, and had the same problem. I thought it might just have been my Internet connection.

I just loaded a video in Chromium 31, and it worked fine. I do greatly prefer Firefox, but for now I can live with Chromium. Is there anything I can do to help you staff figure out what's going on with Firefox?

Okay, so glad its at least working for you in one browser. Can you please make sure that all of your firefox plugins are disabled and then try to load the video? That way we can just absolutely rule out any kind of interference between the browser and the video. 

I used Firefox in Safe Mode and it worked, so I went through and reenabled my add-ons one at a time to see what the problem was. HTTPS Everywhere was causing the problem. Thanks for the quick response!

I'll make note of that incase anyone else has issues as well :) 

@rachitdaiya- Did you try disabling all plugins/extensions on Chrome?