I work sometimes with this type of machinery.
When we put new rolls of material through such a machine, we often put double sided tape onto the roller, to affix the material that is to be pulled through the machine. We do this manually where I work (in the Netherlands), but it appears the Chinese man was too lazy to wrap this tape around the roller himself, so he switched on the roller so that it would pull the tape onto the roller automatically.
Looks like he got his hand caught between the tape and roller, which pulled him closer in and then his T shirt got caught up and he was fucked from that instant.
The machinery we use at my company has several infra red sensors which switch off the rollers if anybody or any object comes close to it. So it would be impossible to do what he did at our company.
But the Chinese don't give a fuck. Faster is better in China. That's why they produce so much crap.
Scrolled specifically through the comments to see a response like this, thanks for the detail.