This is the calc for how much KE nightmare would get from falling off the building in this video.
After examining the video frame by frame, i got 143 stories, aka 471.9 meters.
The video is 30 FPS, and nightmare started falling at the EXACT 3 second mark.
For K.E, you need weight.
Since he is humanoid and male, the average human male weight is enough for now (62.006077 kg)
1 frame = 0.03333333333 seconds, fell for 510 frames, 0.3333333333 x 510 = 16.9999999983
(putting 17 and 16.9999999983 gave the same response)
KE = 25359.24537146 Joules, Wall level.