You have to make sure the send knob (the little knob at the bottom of the mixer channel) is turned all the way down. To undo it click the little orange thing under the send knob.
the reason they called it clint eastwood was because the guitar riff at ~2:15 sounds like a riff from the good the bad and the ugly
the computer maps the mp3s to the vinyls. theyr a special type of vinyl with code written to them letting the computer track their position - its called time coded vinyl. moving them tells the software to move back and forth thru the mp3