Search Support

Avoid support scams. We will never ask you to call or text a phone number or share personal information. Please report suspicious activity using the “Report Abuse” option.

Learn More

The option to open a mp4 file with Firefox is no longer available since changed to 64 bit, how to fix

  • 6 replies
  • 1 has this problem
  • 38 views
  • Last reply by Philip

more options

I have installed the 64bit Firefox, removing the prior Firefox program. Now, when I click on a mp4 and choose to open with, browsing to Program Files/Mozilla Firefox/Firefox.exe and clicking does nothing even when set as 'default' opening program. Am I to have the 32 bit installed into program files x86 or is there something else I need to do? Before when Firefox was installed, it was under program files x86, then the change to Quantum, (ran fine, I could use to view mp4 files), a computer crash with 'Cannot repair member file [l:30{15}]"mozilla.browser"', a new install with change folder 'old firefox', removed prior install of Firefox (one with older install date), now have issue that can't use to open mp4 file from computer.

I have installed the 64bit Firefox, removing the prior Firefox program. Now, when I click on a mp4 and choose to open with, browsing to Program Files/Mozilla Firefox/Firefox.exe and clicking does nothing even when set as 'default' opening program. Am I to have the 32 bit installed into program files x86 or is there something else I need to do? Before when Firefox was installed, it was under program files x86, then the change to Quantum, (ran fine, I could use to view mp4 files), a computer crash with 'Cannot repair member file [l:30{15}]"mozilla.browser"', a new install with change folder 'old firefox', removed prior install of Firefox (one with older install date), now have issue that can't use to open mp4 file from computer.

Chosen solution

Yes, I have installed 32 bit app. The option to open mp4 with Firefox is available and it works. Not sure why the 64 bit app will not work in like manner. Thank you for your time and effort.

Read this answer in context 👍 0

All Replies (6)

more options

Is there a reason you want to use Firefox for watching videos?

It would be better using a video player like; http://www.videolan.org/vlc/


Separate Security Issue: Update your Flash Player Note: Windows users should download the ActiveX for Internet Explorer. and the plugin for Plugin-based browsers (like Firefox).

Note: Windows 8 and Windows 10 have built-in flash players and Adobe will cause a conflict. Install the plugin only. Not the ActiveX.

Flash Player Version: Version 28.0.0.161

https://get.adobe.com/flashplayer/ Direct link scans current system and browser Note: Other software is offered in the download. <Windows Only>

https://get.adobe.com/flashplayer/otherversions/ Step 1: Select Operating System Step 2: Select A Version (Firefox, Win IE . . . .) Note: Other software is offered in the download. <Windows Only> +++++++++++++++++++ See if there are updates for your graphics drivers https://support.mozilla.org/en-US/kb/upgrade-graphics-drivers-use-hardware-acceleration

more options

I have VLC, but when other programs are on top, video goes black while audio is still going. Using Firefox allows mp4 to play.

more options

What your saying seems to indicate Video driver problem. I done that before and video is running in background and audio is no problem. This is with FF58.0.2x64 and Win10x64 FCU 1709. I can play video or mp4 on WMP12 without problem in the background and also load a mp3 and youtube and all gets mixed massed at the same time on speakers.

more options

WestEnd said

What your saying seems to indicate Video driver problem. I done that before and video is running in background and audio is no problem. This is with FF58.0.2x64 and Win10x64 FCU 1709. I can play video or mp4 on WMP12 without problem in the background and also load a mp3 and youtube and all gets mixed massed at the same time on speakers.

?, thanks for sharing. Don't have 10 or FCU 1709. With FF now in program files, instead of program files x86, I can not open mp4 with FF, I can browse for Firefox.exe, select, and takes me back to the open with page without opening file. So....am I to install a 32bit version also to get the ability to use as a viewer?

more options

++Edited++

Many have reported issues using the 64bit Firefox. Install the 32bit version from; Download Firefox For All languages And Systems {web link}

Modified by FredMcD

more options

Chosen Solution

Yes, I have installed 32 bit app. The option to open mp4 with Firefox is available and it works. Not sure why the 64 bit app will not work in like manner. Thank you for your time and effort.

Modified by Philip