Is QuickTime disabled by Firefox on the Add-ons page? Either:

• Command+Shift+a
• "3-bar" menu button (or Tools menu) > Add-ons

In the left column, click Plugins.

Then find QuickTime and see whether it is set to "Never Activate". Unless your version is blocked, you should be able to set it back to "Always Activate" or "Ask to Activate", depending on whether you want sites to use it automatically or require your permission.

If QuickTime isn't even listed, hmm, I have suggestions for Windows but I'm not sure about Mac.

Quicktime isn't listed among the available plug-ins in my Add-ons Manager. Thanks for your help.

As silly as this sounds, please try reinstalling Quicktime. I'm hoping it will add the Quicktime plugin into Firefox.

Visit: http://www.apple.com/quicktime/download/

After the reinstall is done, go back into Firefox's Add-ons Manager, click the Plugins section and tell me if you see Quicktime now. If you don't, we have a pretty weird problem on our hands. :/

Please make sure you are looking in the Plugins section:

Thanks, Noah. I can't reinstall QuickTime because the version I have is essential to my OS. The plot thickens...