Audio Hijack Pro uses the following settings to record audio streams: 1) Application: This works with Camino (isn't it the same engine?) but Safari and WebKit freeze. 2) URL: http://www.bbc.co.uk/mediaselector/check/worldservice/meta/tx/charliegillet?nbram=1&nbwm=1&size=au&lang=en-ws&bgc=003399&enhanced=64&ls=p559
You'll need to take this up with the developer of Audio Hijack Pro. The audio recording you link to uses either Windows Media Player or Real Player for audio, WebKit itself does not create it.