Some things worth noting in video: note how Brumel “gathers” by bending his knees on the penultimate step before the jump, note how Brumel’s lead leg changes from straight to bent as the angle upward increases, note his body does not clear the bar all at once, but piecemeal with his left arm (in this video) and head leading the way and other parts to follow, note how he uses his left arm just after clearance to turn his body downward and twist in a counterintuitive way (upperbody clockwise, forcing lower body counter-clockwise), thus aiding trail leg clearance. Also note that his means his landing is more facing pit (downwards) than looking at the bar upwards, that is, contrary to some instruction, Brumel never looks back at the bar in clearance to make sure his trail leg clears. Rather he is diving and twisting in way that precludes that.