It's probably the actual bass track from the song; I mean who would go through all the trouble recording just the bassline with no clicktrack or any other instruments, you know? It's fine to learn it but...why record just the bass track?
Also, if a guy were going to redo the thing he might be tempted to run it through a rig similar to Squire's; this is obviously direct in with no amp in sight - maybe the direct out from the amp into the board so they could tweak it into the amp sound.
Great playing though. It never really struck me how buzzy/sloppy Chris's bass is setup.
Man, makes you want to go out and get a Rick and some nylon picks.
