Typically the blue part of the flame is hotter than the top, but somewhere in the comments of the vid he said that his hands were covered in water...though I don't know how it lasted that long.
How to make fireballs that you can hold in your hands. Be careful though, it's still fire and can still burn you. Found this vid and thought it was cool.
i just made like 4, i used zippo fluid, only some people can take the heat on their hands, i cant , so i only put a ltlle bit of fluid on the top part, and hold it by the bottom. but you will still get burned so be ready, i dont know if the gas he is using doesnt burn you. but iam sure you can buy it somewere.
Lastly, nearly 90% of the comments on that vid say people burned themselves trying it.
Personally, I don't care either way if you wanna try it. I'm just trying to be helpful and show ways to be sure you don't get hurt. You can take my advice or leave it, they are your hands, not mine.