But it is possible that he had extra batteries in his back pack which he drug behind him in that small sled.
Not so sure about the ski's but I have seen a lot of these types of channels that they bring battery packs for their gear to recharge. They also keep some extra batteries in their pockets or in their coats to keep the batteries warm. This guy seems to only be using 1 GoPro so a couple of battery packs and keep spares warm I would think they can get through the adventure.
I am also guessing that this is not the first time he is in the area. I bet he has done research and is familiar with what he is getting into. But it is dangerous either way.
Happy to watch on youtube...
Sidd
"Life moves pretty fast. If you don't stop and look around once in a while, you could miss it." ..... Ferris Bueller