Firstly, the two fighter were positioned as follows. The foe launched an attack, then Nie Li disappeared and reappeared behind the foe, hitting him and sending him to the position he was before disappearing (well most likely).
I'm going to use the pythagoras theorem to calculate the distance between Nie Li and his foe in order to see how far Nie Li traveled (i don't know how to use the pixel scaling method diagonally in another way).
I'll assume that Nie Li in his panda form is 1,9 meters like when i calculated this explosion.
Nie Li = 25 px = 1,9 m
B = 259 px = 1,9*259/25 = 19,68 m
C = 307 px = 1,9*307/25 = 23,33 m
Here comes the Pythagoras Theorem:
A^2 = B^2 + C^2 = 19,68^2 + 23,33^2 = 387,3 + 544,29 = 931,59 m^2
√931,59 = 30,52 m
So the distance between the two of them is 30,52 meters.
Human perception is 220 FPS, so traveling within a single frame would be inferior to 0.0045 second.
30,52/0,0045 = 6782,22 m/s = Mach 19,77323615 (Hypersonic+)