Don't worry about it. Having actually done some glass blowing myself (I saw it when I was like 14, and so when I got the opportunity to do it a few years later, I was like "FUCK YES!"), it gave me more respect for heat rather than take it away. Being that close to insanely high temperatures (1500-2000 degrees F) makes you fully comprehend that saying "if you can't stand the heat, get out of the kitchen." The radiant heat alone when grabbing some glass can burn you pretty easily if you aren't used to it, nor if you do it properly. If you aren't careful about the glass and you accidentally touch it while it is hot (a mistake you only make once, and one that I have made once), it hurts, but you have to keep going. To say that there are no problems when you are that close to glass though is a bit of an understatement. When you aren't used to the heat, the heat of the glass will radiate up to your arm (you know when he uses those tools and everything) and will be unbearable after about 5-10 minutes. He definitely does have problems, he wants to get it done as quickly as possible so he doesn't get burned, don't mistake his ease and quickness for a lack of fear, it is precisely the fear that is making him move that quick and that efficiently.

edit: it's actually that radiant heat that is the reason he is wearing a long sleeved shirt (if you have short sleeves, you would use socks)