a)they have super-human reflexes
b)they have super-human reflexes
If the Jedi can literally know what is going to occur in a fight--how come they lose 50% of the fights we see them in?? How come large swamrs of them get gunned down in AOTC and ROTS?
"Jedi precognition" in terms of fighting/action is a mix of reflexes and Spidey sense. At other times they have visions and dreams, and can see things literal while in deep states of meditation, but in spur-of-the-moment combat it really just boils down to being able to react quickly to things.
Obi Wan's Jedi Spidey Sense probably told him he could reach the droid in time if he dove through the window right then, but there's no way he could know anything else, including that it would support his weight, that it wouldn't be rigged to explode if captured, that the assassin who shot the droid wouldn't shoot him in the face, that it wouldn't simply drive into a building and kill him, and that Anakin would gently pick him up from freefall into the passenger seat of the speeder.
It's a nitpicky thing, for sure. I think his note that it would make better sense for Anakin to do this is far more salient, because this has to do with character issues. But I have to say, nitpicky or not, he has a good point nonetheless.