If you want to record audio from your Windows computer outside of ableton such as capturing audio from your favorite viral video, follow these steps…
On PC, download and install VB-Cable.
You will also need to download and install Asio4All in order to allow for proper routing in Ableton Live
Change your playback device to route out to Cable-Input (VB-Audio Virtual Cable). In Ableton Live, change your Driver Type to Asio, your Audio Device to AsioForAll v2, Then go to the hardware setup. For simplicity sake, mute all inputs in the Asio4All panel that are coming from your soundcard or interface, then enable the Device in the panel called VB-Audio Virtual Cable, then underneath the device, enable the IN (NOT THE OUT). Finally, enable your soundcard or interface device in the Asio4All panel, and enable the OUTPUT of that device only.
If you arm an audio track with the audio from on Ext In and change the input to 1/2 so that you have stereo audio in, you should now be able to hear and record your computer’s audio from video in your web browser and other sources running through Ableton Live. Make sure to set the track Monitor to “Auto.”