Usually .mov will be played by QuickTime. Could yours have gotten disabled? Check here:

Tools menu > Add-ons > Plugins category

Sometimes plugins are disabled if they are old and have security problems...

If it's not disabled, are you sure you have it installed? For some reason I thought it would be pre-installed on your system. Maybe it needs an update?

QuickTime was not installed. I checked the Mozilla Plug-in page but a search for QuickTime yielded no results. How can I upload QuickTime?

I think you need to install the full player package from here: http://www.apple.com/quicktime/

Note: You do not need the "Pro" (pay) version to watch media, only for authorizing.

Can't install QuickTime from the link you supplied (I'm told it's already installed on my Mac) and it's not available from the Mozilla add-on manager.

Aha, you already have QuickTime. Unfortunately, Firefox didn't find it. Can you try the method described in this thread (deleting a file and having Firefox re-generate it) and see whether it works for you?

Firefox 19 will not load quicktime plugin.

Tried that but Firefox 18.0.2 still can't find a QuickTime plugin. I'm running Mac OS 10.6.8 and did not have this problem with earlier versions of Firefox. So... something else to try or back to Safari?

Try updating to Firefox 20

Firefox 20 didn't solve the problem!

See also:

• https://developer.mozilla.org/en-US/docs/Gecko_Plugin_API_Reference/Plug-in_Basics#How%20Gecko%20Finds%20Plug-ins

There have been some complaints on Apple's forums about this. Something may have changed in the location that QuickTime places the plugin Firefox needs. The article cor-el linked above shows the folders Firefox checks for that file.

According to one old screen shot, the file name is "QuickTime plugin.plugin". If you can find that on your system, you could try copying it into one of those folders.

If it's already there but not recognized, I saw a suggestion to start Firefox in 32-bit mode once -- check about:plugins to confirm that it was recognized -- and then you can go back to 64-bit mode.

You can also look at this MozillaZine forum thread.

• http://forums.mozillazine.org/viewtopic.php?f=38&t=2642633

cor-el found the solution. Thanks! I followed the thread http://forums.mozillazine.org/viewtopic.php?f=38&t=2642633 and created a new user profile. That did it!