Using the 3 data points that are clear right before the hit, I can get an average foot speed of 6.3 m/s (14 mph) with a velocity vector of (-5.85,2.39,0) m/s—this will be important later. Also, the foot has a recoil velocity of (-1.26,-1.04,0) m/s. Notice that this analysis doesn’t include the motion of the foot in the vertical direction (since I can’t see that).
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Now for my first wild estimate—the mass of the foot is about 1.2 kg based on Holly’s weight of 134 pounds and this paper on mass distributions of the human body. Yes, it’s actually more than just her foot that hits Rousey. How about I use an adjusted foot mass of 2.5 kg (just a guess) to take into account the mass of the rest of her leg?
Now for the impact time. I can switch to a better quality video (but not viewed from the top) to estimate that. It looks like the foot was in contact with the face for about 2 frames. With a frame time of 0.033 seconds, this gives an impact time of about 0.066 seconds.
Putting this all together, I get an average force during the impact with a value of (173.9, -130.3, 0) Newtons and a magnitude of 217 N (48.7 pounds).
