Thanks for your help, Stream Recorder. If you got the 62MB file then you too are getting the whole mbr stream: just play it in wmp and check the size of the .dat file stored in your Temporary Internet Files folder or open the wmv file with Windows Media Stream Editor and extract the highest bitrate.
My guess would be that, unless there's something wrong with our settings, the stream recorders we've tried don't support the Intelligent Streaming technology wmp uses. I'm pretty sure that dial-up users are able to play the stream in real time but get the 62MB file too when recording it.
In case I didn't make it clear before: those live streams I'm trying to record, I can play them smoothly but record them with gaps only.