Okay, there's a lot going on here so let's break things down. Is it impractical to use quadcopters to tow a toddler on a snowboard? Yes, very. Did the battery on the drone in this video last long? Probably not. Did the kid go very fast? He's barely moving. Is this a great idea? Of course, of course, of course.
Using a consumer grade drone to tow people on snow (or on water?) makes about as much sense as strapping a giant fan to someone's back while they're paragliding — but people do that and it looks like great fun. And while drones may be pretty weak with batteries that only last tens of minutes, they are at least getting stronger, and we can definitely imagine a team of drones pulling a fully-grown human. Maybe they could do it on a sled? Like huskies? Hunting down rogue robots through the future-frozen wastelands of middle America after the coming Ice Age / AI revolt??
Okay, that's too far, but this is still pretty alright.