I'm a Debian user, but for what it's worth I see exactly the same
problem with iceweasel 3.0.6 (what Debian call firefox). Youtube is
fine, and I see the volume control, etc. in the Onion site, but the
actual video doesn't come. I am also running AMD64.
--
Videos from www.theonion.com
https://bug
** Attachment added: "Dependencies.txt"
http://launchpadlibrarian.net/25704500/Dependencies.txt
** Attachment added: "ExtensionSummary.txt"
http://launchpadlibrarian.net/25704501/ExtensionSummary.txt
** Attachment added: "profiles.ini.txt"
http://launchpadlibrarian.net/25704503/profiles