Vulcanized rubber tends to burn more easily than it melts. You could melt them back togeather but you need finer temp control than a normal torch offers. Odds are they were just glued back togeather. It’s not like they’re being used on the road so you don’t need to worry about the glue holding up under those conditions. I’m also pretty sure I can see the line in the video where they were cut and glued.