YouTube crashes

[GreatEmerald]

I have just recently set up an IPv6 tunnel (going through Warsaw, PL: tserv28.waw1.ipv6.he.net ). However, there seem to be issues with it and YouTube: every several minutes playback stops with a generic error. Reloading the page results in the video resuming, but crashing after a few minutes again.

I'm using Firefox 38 on openSUSE 13.2, YouTube HTML5 client. My router is running DD-WRT with radvd. The issue happens with both privacy extensions enabled and disabled. When I change gai.conf to prefer IPv4, everything works perfectly well, but obviously over IPv4.

There's a related topic, but it's rather old and for the London endpoint: https://forums.he.net/index.php?topic=2562.0

Anyone else having such issues? Perhaps there's a way I can debug this?