Tigers are ambush predators, which means they are designed for explosive bursts of speed and amazing leaps. I'm not surprised they could jump up on an elephant given proper motivation, although this doesn't seem like a tiger hunting- it looks more like a defensive attack. I can't imagine a tiger would willingly try to run at an elephant- those things are huge and dangerous. In fact, I read something years ago that said more people are killed by elephants than any other animal. I don't know if it's true or not, but even so they aren't the kind of prey that tigers usually go for since they are designed for a quick kill.
Def