Bug/Secret at the loading screen

Hi there is a little secret on the loading screen. Theres the running guy yeh and when u press space he jumps but on one video i saw him jumping very high look:

(the jumping guy starts at 0:45)


Can u help me because i dont know how can i jump that high with that guy.

.............................wonderful discovery?i look yp to u now

I know its old but on the video he jumps so high how?