sufcdan - I also received your support e-mail, but it looks like you've made progress so I'll reply to you here instead.
O2's 3G network is exceedingly complex when compared to other networks around the world, so I am glad to hear that you are now able to connect via 3G.
There shouldn't be any difference between receiving audio and video, however, except for the fact that you have less bandwidth to receive data with. Are you still unable to receive audio when connected via 3G?
One test to try to see if maybe a setting on your computer is having an affect as opposed to the connection type is:
- Connect via WiFi and confirm that you receive audio and video.
- Temporarily disable WiFi on your iPhone to force it to connect via 3G to see if you lose audio.
- Re-enable to WiFi and see if audio returns if it was out with 3G.
It may take longer for the audio to start over 3G just because of the bandwidth limitations, but it should still work.