Youtube video flaw with an IPv6/IPv4 dual-stack client

I wrote four years ago:

I am very happy with my HE IPv6 tunnel. Szívesen lennék natív IPv6 felhasználó is, de az UPC nem ad információt, hogy milyen IPv6 tervei vannak. )-:

UPC Hungary has shown no progress since then so I still have to use the Hurricane Electric tunnel. There are some changes though. Google, Youtube, Facebook, Cisco and other big portals have switched to IPv6/IPv4 dual stack (at least the public facing services) so the amount of my IPv6 traffic has increased. On the other hand, I am unable to watch some Youtube videos due to a Youtube bug.

IPv6 host’s default router selection

An IPv6 host’s default router selection is affected both by manual static routes and received router advertisements.

I am very happy with my HE IPv6 tunnel. Szívesen lennék natív IPv6 felhasználó is, de az UPC nem ad információt, hogy milyen IPv6 tervei vannak. )-: I bookmarked Google’s IPv6 site but once it turned inaccessible. What could have happened?