Interesting, it seems he was trying to get back on the train because his bag was still on there... if you see near the end of the clip another passenger brings out his bag for him! Bloody idiot this student is, regardless you should be able to control yourself, i know many diabetics and never seen them be like that kid .
Violence isnt the answer always but i agree he was right to do it, simply because the student was being abusive and had apparently 5 minutes before the clip even started to explain any real issue (the guy who filmed it was on the tv?) and the "big man" even asked the conductor if he wanted him moved, the guy clearly grabs the student and says move and yet he still doesnt so the guy continues to push him and eventually gets him off the train, the student trys to jump back on and at that point the guy simply uses the student momentum against him, simple really!.
Im sorry but i cant see how we can maintain the, if he wasnt being violent and endangering anyones lives he should have been left to it. Its silly because think of it this way, if someones got an extremely important thing to get to i.e court or something to do with getting custody of their kids or going to a job interview, they're being held up by this idiot and could potentially screw their lives up for good, its not violent but it can have a knock on effect for people.
Hes a dipstick pure and simple, man up and take it on the chin to never be a prat like that again.