It seems that in any dying project the bureaucrats, middle managers and otherwise challenged people are the last to leave. They cling on to past greatness and try to re-evoke what is gone.
The last Firefox update 22 put the latest available Quicktime Version 7.6.8 on their blocklist. Clips will not longer play, but a warning will show up, requesting an update. Only problem is that Quicktime 7.6.6 is not out of date for OS X 10.6.8. FF has acknowledged this and it is fixed. But a download of FF still has the broken blocklist.xml.
If you want or need to fix this manually you can do:
1) locate blocklist.xml for instance via
2) remove the 3 lines:
<pluginitem blockID=\"p408\"> <match name=\"filename\" exp=\"QuickTime Plugin\.plugin\" /> <versionrange minVersion=\"0\" maxVersion=\"7.7.0\" severity=\"0\" vulnerabilitystatus=\"1\"></versionrange> </pluginitem>
3) restart Firefox