Try it if your current version works then all being well that one will also.

Firefox are no longer officially recommending the earlier versions due to a security update. There is a workaround of turning off protected mode that some users may need to try if up-to-date flash versions do not work with Firefox Windows.

• http://kb.mozillazine.org/Flash#Flash_Player_11.3_Protected_Mode_-_Windows
• http://www.adobe.com/support/security/bulletins/apsb12-18.html
• and to check for the latest version http://www.adobe.com/software/flash/about/

I'm presently using 11.3.300.268. When I tried to use 11.3.300.271 I had problems-no video on YouTube. I spent about 4 hours trying to get FP to work so I just went back to .268. That's why I'm a bit leery about upgrading until I hear from some other users about their experience with the new FP version.

You are on an insecure version of Flash Player, but my understanding is that the security exploit requires opening of a malicious document, and so possibly a careful user may avoid exploits.

Did you look at the articles I inked to. The chances are that if you turned off protected mode both the newest 11.4 version and (11.3).271 will work. To disable protected mode a line ProtectedMode=0 is added to the file "mms.cfg" the mozillazine article gives full instructions.

I am assuming .278 is a minor release of 11.4. Keep your eye on the thread [/forums/contributors/708573] someone from Firefox may provide more information. You may also find that the mozillazine articles are updated faster than the official Firefox articles.

You could even consider trying use of Flash 10.3, Firefox will not officially recommend that, but observations suggest Adobe is keeping 10.3 updated.