It is though. I went full "mixed martial autist" and played the original video next to the gif and in the gif version Mike completes the 180 ° turn faster. It might have not been speeden up as much as I originally thought, but it still is.
Not only that, but things looked way faster on older cameras that had fewer frames per second. Your mind fills in the blanks subconsciously, while also simultaneously predicting the next frame, and even a tiny FPS difference can make things look way faster than they are. In the early 80s, a camcorder like the one we see filming this shadowboxing was at the absolute most running at 30 FPS interlaced, which would translate to the viewer seeing about 15 FPS. The footage is awful, obviously not a top of the line camcorder, and you can see it was interlaced by the visual distortions, so it was probably an even lower framerate.
Now imagine you have 3 frames; one frame shows the punch chambered, the next frame is the middle of the punch, and then the third frame is the punch fully extended; played back to back, your brain autofills the blanks and thus the punch appears to accelerate at ridiculous speeds, but if the camera was running at 1 FPS that would in actuality be an insanely slow punch, 3 seconds from start to finish. Even though the footage is running in real time in the Tyson clip, your brain is still trying to fill in the space between frames as if you placed them back to back, and as the punch extends it's also trying to predict the acceleration, which is then translated in your brain as being much faster than it really is. It's why Bruce Lee had to slow down his strikes for the old 60s cameras in his movies, or else the movements would look choppy and unnatural.
Here's a video showing a good example of it, the difference between 24 and 60 FPS. The bottom one looks like it's moving much faster because of your brain's interpretation. You'll notice that if you look at both at the same time, the bottom appears to decelerate, letting the top one "catch up" and then accelerate multiple times, because your brain is comparing it to the top one and trying to rectify the illusion, but if you only look at the bottom one you won't see that deceleration effect.