I'm not defending Apple's decision (or lack of action) in implementing this feature in the core system, however I would like to point out to you that Mac OS X has a native VLC client, download that, if you go and play a song or movie, then go to the "Playback" menu and see the "Faster" menu item. Hit it twice for 2x playback speed. This makes voices talk quickly without altering the pitch, therefore there's no chipmunking. This is surely as simple as the "installing 2xAV' as you mentioned above for your PC.

I'm not privy to the list of supported BitTorrent clients for Ipodnova/videoseed, however you did mention Utorrent, and this also has a native Mac client available. I would assume that the Utorrent guys use the same implementation of the BitTorrent core protocol, so you should be able to use it just fine on those sites.

I'm interested in how you achieved this too, please can you share the details with us?