Think it was on last year, George Martin talking about how the songs were recorded, etc. I downloaded it via torrent.

There's a bit where he's talking about Taxman, and how the guitar/bass/drums were recorded onto one track. The presenter says "But due to groundbreaking technology we can now hear Taxman as we've never heard it before." then George Martin says at Abbey Road they've managed to isolate the bass/drums/guitar separately in the recording and they play a bit and the guitar is muted but you can still hear the bass and drums and basically I'm wondering how they've done this cos I always thought that was impossible.