Are you talking about the part from around 8 to 8.5 minutes in? I was impressed throughout, but that absolutely requires a lot more strength than people would give credit for just watching without holding one of those.
@Wing Woo Gar if I read right in the other thread, that was your sifu correct? Very impressive, you are lucky to have trained under him. At 10:30-10:35 he also has a conditioning drill built into that 2-person form that is incredibly effective, but I've only ever seen done in my first school as a kid (and the later instructors when I went back to that school after college did not know it). Until just now, wasn't entirely sure if I made it up in my head.