For the last few months Gnash has had a problem, with cookies on YouTube. The issue was you always get a "an error occurred, try again later" message instead of the video. This required the user to block all YouTube cookies as a workaround.
For the curious, the problem turned out to be the cookie YouTube sends had regional information setts in it that required those same values to be retransmitted with the HTTP headers, or Google's server's wouldn't handle the redirect correctly. This used to work correctly in Gnash using XPCOM, but XPCOM has been depreciated. So the new support uses NPAPI to do the same thing in a much less complex manner. I finally fixed this a few days, (revno #12202). New deb & rpm snapshot packages without this problem are on our http://www.getgnash.org site. This used to work correctly in Gnash using XPCOM, but XPCOM has been depreciated. So the new support uses NPAPI to do the same thing in a much less complex manner. Also Gnash should now work with all YouTube videos, thanks to some help from the YouTube developers at Google. :-) - rob -