I didn't even know that YouTube had multi-channel audio. I'll need to check it out sometime.
EDIT: I'm trying out a youtube 5.1 sample on the PC. I never noticed this before.
Roamio Pro (5TB Red)
TiVo Mini x4
Roamio Basic(1TB Red)/Roamio Basic refurb(stock drive)
53TB unRAID2--38TB unRAID3--33TB unRAID1a