It gets more than hot enough to melt solder, about 200 degs C, but like all soldering irons as the tip is small it doesn't RETAIN much heat (i.e no heat sink). It does score because it's tries to replace the lost heat quickly.
My old 400w iron has a tip on that must weigh about about 0.5 kilo (solid copper) but when you touch that to something large you know the temp. wont drop quickly and the heat is being transferred to the job. Same old, same old; "Horses for courses!"
I think his point (whoops!) is, that as he works his way along, only the bit between the tips gets really melted, the rest remains together because he isn't in contact very long. A bit like Mig welding, the heat path is very short, so he can 'progress' the joint rather than trying to kill it in one go and needing loads of heat.
