Wrist extensors pain from wrist pushups?

I've been progressing on the wrist pushups for some time and i have no problems with the ones on the palms,but the ones on the knuckles where you bend the wrist like the athlete on your video cause me great pain in the wrists.What could cause this?I don't get this pain when for instance i try to do reverse wrist curls with big dumbells.I also use a soft surface for the pushups.

Shortening my ROM fixed the problem for me. As long as I stay on my knuckles I get no pain.

I began with elevated wrist pushups. First I started it with my feet on the ground and my wrist on my bed. Then I slowly found lower and lower objects till I could do it on the floor. The entire transition took me 3-4 weeks. I must say this really helps with hand balancing, I use to have very weak wrists. And yeah I recommend doing it on a soft surface or placing a towel under.