I agree, looks to me like they managed to take it down so as to not recover much.
The stuff hanging from the balloon looks like a solar array with some antennas at the ends.
The big black circle at the bottom of the balloon, lack of a hanging equipment gondola, and the pentagon saying it has propellers, according to the narrator, suggest that there is hardware inside the balloon above the black spot, possibly retractable in daytime. Airships used to have structure including walkways inside the envelope.
The video shows the sidewinder hitting the base of the balloon, as you say, which is counterintuitive if you accept the narrator statement that it was targeting in the optical band. It could be the black spot was hotter than the envelope, but I doubt it. The top part was reflecting direct sunlight.
My point is the missile probably hit the part of most intelligence value, and detached it from the balloon which would otherwise have made it fall and hit slower, like you would want.
Maybe they didn’t want to recover anything of intelligence value. Or maybe they thought the payload would self destruct more effectively if only the balloon were damaged. Maybe the black spot was hot because it was radiating a lot of power dissipation from electronics and the sidewinder was just doing what sidewinders do.
!! Baloney. This was all about SIGINT, not sightseeing or meteorology.
Nothing two orders of magnitude less significant than this comes out of China without being a closely calculated, CCP/PA event.
The AIM-9X missile, the one that the F-22 used to engage the balloon, has an imaging infrared sensor, which can lock onto a target both by its heat source and by its infrared shape. This is to reduce the ability to decoy the missile with infrared flares, which while being a much stronger IR source than an aircraft, would have a vastly different shape.
The AIM-9X cannot be targeted at the instrument package or the balloon envelope discriminately. Nobody purposely targeted the balloon in such a way as to not be able to recover anything. That's akin to asking the police to shoot the gun out of a bad guy's hand instead of just shooting for center of mass.
The AIM-9X has an imaging infrared sensor that locks onto a heat source, then tracks its shape as it approaches. This is to minimize the ability of hostile aircraft to decoy the missile with infrared flares. The flare would be a bigger heat source, but not match the shape of the initial target at lock-on, so the flares would be more likely to be ignored.
The balloon envelope would be at the same temperature as the background air, so it would not be an easy IR target. The electronics package, however, would be giving off heat.