When you consider Kirby rarely used photo reference, you have to think it was pretty uncommon for Jack to look up from his drawing board when facing a typical crushing deadline, so he is doing a pretty nice bit of acting here. Jack's Hulk TV appearance is from 1979, so I wonder if Kirby filmed this right after he left Marvel and began working in animation.
Here's the splash page of Machine Man # 9 (1978), "In Final Battle," Jack's last published book for Marvel Comics containing all-new material, dated December 1978. In honor of the Kirby-signed baseball I posted a photo of last week, I also included a few images of Machine Man in action from this issue (page 9, panels 1 - 3).
Looking through this last issue of Kirby's Machine Man, it's pretty obvious that when Jack stopped producing comic books in 1978, he was still at the top of his game. Three years later, in November of 1981, Jack would return to comics with Captain Victory and the Galactic Rangers # 1, art by Kirby and Mike Royer, with beautiful colors provided by Steve Oliff. Here is one of my favorite images in that book (page 5).