desktop users who are streaming video with a proxy are likely paying for a commercial (=high bandwidth) proxy service, rather than the free (=low bandwidth) tor network..

nope, you don't need to worry about the bridge ip. Probably a dumb question, but - once tor was installed, did you actually enable it (via its status icon)? It is inactive until you specifically turn it on. Likely not the issue, but thought I'd mention just in case. If not that, I'd suggest posting for help on a tor-specific thread, where someon more able to diagnose/fix your issue may be lurking :-)

BTW - I have in the past managed to run iPlayer on my N900 via tor (on a WifI connection from abroad) - but not for any length of time, and with plenty of buffering - however there's no reason why you couldn't use the download feature of iPlayer with tor to get around that. The one that stumped me was the 4OD (channel 4 UK) player - it is a horrendous bag of spanners (to enforce the mandatory watching of the embedded adverts) an while proxying to a UK IP will get the replay started, it craps out following the intro with an error that is (superficially) unrelated tot the proxy, just says that the session has timed out ... but restarting doesn't help and I can't find any way around it. Oh well, just have to go out and have fun while abroad instead of watching UKTV on the TV out in my hotel room :-)