Upgraded to 6.0.0.066 a few moments ago and if I turn Replay Media Capture to AUTO ON I can no longer access Youttube videos. I tried various videos and get this message:

Secure Connection Failed

An error occurred during a connection to www.youtube.com. Peer's certificate has an invalid signature. (Error code: sec_error_bad_signature)

The page you are trying to view cannot be shown because the authenticity of the received data could not be verified.
Please contact the website owners to inform them of this problem.

If I turn AUTO OFF I can refesh the page and see the movie.

Using FF 35.0 on windows 7 64bit machine with 8G ram.

Also - can down load the same youtube video by going back to version 5.0.1.54

BTW: Where is the "About" button/tab in version 6? Must say I liked the previous versions user interface and color scheme much better. This tew-tone interface is not helpful.