I couldn't catch whether he said (17) or (70) when he talked about the spare rounds carried on-board. Did you catch that?
He isn't very clear is he, but based on what I heard he said:
22 rds in the carousel (for the auto-loader)
17 rds in storage compartments inside the turret
2 rds in the external storage compartments (probably in the turret bucket on the back)
41 in total
I checked my old Janes Main Battle Tanks book to verify the total number he mentions and it matches the number of rounds carried internally (39). Jane's says rounds are split out as follows:
12 APFSDS (armor piercing fin stabilized discarding sabot),
21 HE (high explosive) and
6 HEAT (high explosive - anti -tank).
For what it is worth, the number above (39) matches the wiki page that refers to a T-72 manual as it's source.