mine is year 13 with 23K mileage only and have same sound as OP. i heard our TOB is spinning even clutch is not engaged so i am not sure this is normal or not. hope others can test theirs and post here with year + mileage to see.
i am also thinking it is Input shaft spinning in the transmission as some others are saying though.
everything works perfectly so
if it is indeed TOB, then i will just upgrade my clutch with new TOB While it's there.