So I looked at this clip and I've always been wary of heat imaging because the visual doesn't usually match the physical shape of the object.

If you fly a quadcopter at full throttle, it'll assume an upright, almost 90 degree position. The motors will get warm and may generate enough heat to travel along the arms of the quadcopter. In this clip the heat signature, especially when it zooms in around the middle of the video, seems to be uniform across the entire object.

But it's real life context that hurts this explanation. If the quadcopter is electric battery powered, it wouldn't be able to maintain that high speed stance for 4 minutes. To cover that much distance it would be much more efficient(and logical) to use a fixed-wing aircraft flying in a horizontal stance.

I wondered if it might some type of antenna array attached to a craft that isn't putting off heat or has some kind of stealth tech to hide the thermal signature of it's propulsion system. But if the VTX is that hot, it kind of defeats the purpose.

1:06 in the video: Looks like it might be some kind of oblong balloon but I'm having trouble understanding how the heat signature correlates to a balloon. I've taken thermal imaging of a hot air balloon and the heat image exactly matched the balloon's shape.

Heat signature of a hot air balloon(white hot):

Source: https://www.youtube.com/watch?v=sfeA2SrMujc