I'll try that shortly. Not sure how much difference it would make since completely disabling Internet connection doesn't seem to help either.

EDIT: Added networks I use to automatic (home WiFi). No difference (probably since I'm not at home when I'm watching videos). The idea is to avoid having to be connected when watching videos - currently the only solution for me appears to be to actually be connected (either via 3.5G/WiFi) to a network. The battery life on the N9 despite being an improvement from the N900 in some ways definitely isn't enough to make me want to watch videos while having a 3.5G connection.

I should probably file a bug report on this some time soon.