How can I copy a song onto audacity without using speakers?

I have to record the backing track of a song from youtube and I have audacity already but I don't know how to record it without using a microphone and speakers. Please help!|||In Audacity: Edit --%26gt; Preferences





Under the "Recording" section, select "Stereo Mix".





Stereo Mix records exactly what audio your PC is playing, so there is no quality loss.





If Stereo Mix is unavailable as an option, do this:





Windows Control Panel --%26gt; Sound --%26gt; 'Recording' tab





Right click any device and select "Show Disabled Devices" and "Show Disconnected Devices".





Stereo Mix should show up.





If it STILL doesn't work, go back into Control P --%26gt; Sound --%26gt; Recording and set Stereo mix as Default.





If it **STILL** wont work, try first downloading the video from YouTube (using something like 'Fast Video Download' for Firefox [Free] or similar) then convert the resulting .flv file to MP3 with a utility such as WinFF (Free).





I usually use the last method, as that way I don't have to time when to press the "Record" button in Audacity, plus I get the actual video downloaded to my computer as well.