Here's a verbal report on the same story, saying the Rottie weighed in at 110 lbs. - did you see how fast he was jerked up by his neck - and his owner broke 2 fingers trying to get him loose when the leash finally snapped. I thought she's somehow managed to get the collar unbuckled but thankfully the lead just broke.
https://www.youtube.com/watch?v=VKOVw7OFFG0
Yikes, here's a pug dog going through the same thing when owner gets into an elevator with pug on the lead, pug runs back out of the elevator, doors suddenly shut and up goes her leash with the owner in the elevator, suddenly jerking little pug up from the outside! Can't tell but it looks like the pug's lead snapped too or somehow the bystander got it quickly unhooked.
https://www.youtube.com/watch?v=ADEzpL3bTFs