Source: https://www.youtube.com/watch?v=5bUSxQwt4x0

This one has been around for a while, the original YouTube video is from 2014. But it seems to have gotten renewed interest.
My initial observation is that it's pretty consistent with a balloon tethered with fishing line. It also strongly resembles the Sputnik 1 satellite.

So my first guess would be someone, maybe school kids, making a sputnik model out of a large sliver helium balloon, and then flying it.
This one has been around for a while, the original YouTube video is from 2014. But it seems to have gotten renewed interest.
My initial observation is that it's pretty consistent with a balloon tethered with fishing line. It also strongly resembles the Sputnik 1 satellite.
So my first guess would be someone, maybe school kids, making a sputnik model out of a large sliver helium balloon, and then flying it.