What do you think about the events in this video...

…without any other information but’s what there? (at least for the moment)

It's just three minutes - and you can probably skip to the end the first thirty seconds, nothing particularly different happens in the middle.

Tell you why I’m asking after a few replies.

I think I have no idea what was happening, what any of those people were saying, or why you are curious about any of it.

Without any more information, I’d guess he was probably doing something to provoke them.

Looking for more info, and reading the first random article I found about it, it appears he did so. According to that one article, the transit police (which appear to be something akin to private security) tried to detain him for not paying his fare and he tried to run. It happened a few times so they called the cops and this is how they happened to pin him.
Granted, they could have cuffed him and sat him on the ground, but we don’t know what happened in the seconds before they grabbed him and we probably won’t.

If he was fighting with them as they attempted to detain them and he put his back into the wall then it was him who made it convenient for them to bend him over it to keep him in one place. FTR, I don’t know that this is how it played out, it’s just a thought. For all I know they tossed him into the wall. I’m just saying it’s not fair to immediately assume that cops are evil because we have half of an arrest scene where someone looks like they’re getting roughed up. We don’t know what led up to it.

Seems like there would have to be more video available that precedes what we see here.

What does ‘touched on’ mean?

It’s the electronic ticketing system (he talks about a Myki too - that’s what the ticket is called)

You touch on at the start of your trip and it dings you the cost, touch off at the end.

If by any chance you don’t touch on at the start and you see station security at the station you get off at, you may choose to try and “touch off” (it’s the same machine) and go on your way. However, if you weren’t touched on already, the machine will say “touched on” (because it will think you’re coming in, not going out), and if security sees this, they will realise you were travelling without paying.