Monfils does more acrobatics than anyone, he doesn't fall and go off-balance more than Djokovic, quite the opposite actually. Also, if you look at Nadal's and Federer's slides for example, they are much more balanced than him(not to mention some former players like Chang and Mecir).clips 1 and 2 are really rare occurrences. novak slips a lot more than other players, but it also has to do with the fact that he does the most sliding, splitting, stretching of anyone in the men's game. I'm sure any other player would fall even more often if they tried the acrobatics novak does every point
Balance just isn't Novak's strength. It's probably the main weakness to his mobility, along with the forward/backward movement.