Stolen bikes

There are professional bike thieves in London who I'm sure use these type of bolt cutters. You can buy them easily.

stolen actually, they tend to be stolen, usually from fire station.

if you persist with the video he breaks some of the chains in an elevated position.

Im not here to argue ED, but the proof is there to show that chains break easily, they are vulnerable to attack.
Remember also that those chains in the video are the better, more expensive heavy duty motorbike chains. Lighter smaller gauge bike chains would break muich easier.

I would never recommend anyone to use a chain on their bike.

I seen the video years ago, what you didn't notice is how loose the chain was, hence Snoops advice on making sure the chain is wrapped nice and tight, as oppose to just one loop on the front wheel of a motorbike allowing the theft to cut the chain any way he like, that why it break easily.

like I said, it's the locking technique that make the difference.