it could be he's using some distortion pedal...or he cud be fiddling with the switches...either that or he might have changed the pickups of his guitar...dont worry about your guitar there's nothing wrong with it! im pretty sure the clip you saw he was using some distortion pedal like a flanger or a chorus or a wah wah pedal it could be anything...dont worry about that as of now and just focus on practising and improving dexterity.... :)