Virtual Audio Streaming is a virtual sound card that allows you to record any and all audio, including online movies/videos/audios, Skype calls, etc. Any audio you would normally hear from your headphones, speakers, etc. can be recorded by Virtual Audio Streaming and saved as an audio file. It can also broadcast/stream audio streams.
Virtual Audio Streaming simulates a sound card on your Windows. You can use it as an enhancement of your physical sound card.