Recording Audio in Sound Recorder

Click the Start button , click Control Panel
click, SoundSelect Recording Tab,
check box for Show Disabled Devices

Hover over Stereo Mix, Right click Enable
Right click and open Stereo Mix Properties
Select levels Tab set slider to 100.

Open Sound Recorder, play Youtube video,
Select Start Recording on Sound Recorder,
Stop Sound recorder at end of video, save as file.wma;
Playback with WMP