I think I can verify this is definitely Ethernet driver issue. Having read quite a lot of posts in Pi forums I found out that Raspberry engineers acknowledge there is a severe issue with RX flow control of the driver. I wouldn’t expect a quick solution.
Pi forum provided me with a workaround that I can live with. By forcing Ethernet interface to 100 Mbit/s it won’t drop frames, doesn’t get clogged and stays alive.
First I installed ethtool, then did what someone suggested in Pi forum and added following command to /etc/rc.local
/sbin/ethtool -s eth0 speed 100 duplex full autoneg on
EDIT: I’m having some problems with this command and /etc/rc.local - have to investigate a little bit…
EDIT2: I had to delay execution of rc.local until network is ready. Luckily there are instructions.
100 Mbit/s is quite all right and I can watch my recordings uninterrupted again.