Problems with 50+% of YouTube videos

[MR ZenWiz]

I'm running Xubuntu 12.04 and a couple of days ago I updated to the
latest kernel.  I don't knwo if this is related, but on my home
desktop, suddenly about half of the YouTube videos I want toplay are
not playing.  I can't even use youtube,dl to get them.

This morning I tried a few at my work desktop, whic his also running
Xu12.04 and I had no trouble there.

Usually this works the other way around (we have a firewall at work
that catches a lot of "security" concerns - mine at home is more or
less generic).

This happens in FF, SM and Chrome, and clering the cache doesn't do any good.

Where else should I be looking?  I'm no at all familiar with setting
up my firewall, so if there, guidance would behelpful.

Thanks.

MR