If VINO or somebody else can tell you how to do this easyer, if you open the stream up in QT Pro (will still need Flip4Mac), you can export it to MP3 as shown below.
Otherwise you could use one of the two following methods. (recycled from a previous post)
1.) Use audio routing and combined recording programs.
Get and run one of the following programs. WireTap is a routing and recording program similar to Audio Hijack. You can rip and record from streams, DVDs, speakers, jacks, and the microphone. Both are good programs, and the limited version of WireTap is free. Each of these programs allow you to record from the mic, system, and in some versions from other sources. I like WireTap Pro, which is less expensive, but has fewer options. Both are good, really.
2.) Use an external audio routing program with a recorder. Here are two free options. For free audio routing I would use Cycling 74 Software offers SoundFlower and SoundFlower Bed for free. There are others, like Jax or use Jack Tools-also free routing. There are complaints that they are glitchy, but I haven’t had problems. I use SoundFlower (see above) though. Once you load any of these programs, you can set audio output to go to a channel and then record from that same channel as a source. A good ultra simple recording app is Audio Recorder.app- It has some other features, like recording on a schedule It also has a clip warning. Another free recording app is Audacity- Free/open source cross platform audio editor For a free product, it really is good. Add the LAME plug-in for MP3 conversion. It is VST and NYQUEST plug-in compatible. There are at least a few hundred plug-ins that it can use-so have at. It was programmed in JAVA and is open source, so the code is not completely optimized. In short, a lot of overkill and a bit slow at times.
Once you decide how your going to grab the audio, play the stream (which really isn't a stream) and save the file. Depending on the recording software, you may need to convert the .wav, .aiff, or what ever to MP3.
Post script: VINO- that is the cutest avatar based on a real pictures that I have ever seen!