1) There's a range of speeds that are possible depending on what you assume the turning angle of the jet was. That range doesn't go anywhere close to the speed of sound.

2) The burden of proof is on those who make an extraordinary claim. There is a perfectly mundane explanation of the cause of apparently fast-moving object which is supported by available evidence. Even if that depends on some assumptions, you would have to demonstrate those assumptions to be false before a less likely alternative, i.e., that it was an extraterrestrial spacecraft, should be adopted.

A perfectly mundane explanation isn't proof. There isn't enough evidence in this case to prove it one way or another. That should be acceptable but for many people it isn't.

In that situation, though, https://en.wikipedia.org/wiki/Russell%27s_teapot applies, as we can’t prove the negative.

You are making the assertions here. You claim to know the speed of the object, the distance to it, the size, etc etc.

No, the assertion being made is that there are mundane possibilities for each of those values that have not been ruled out by the data/video we have.

To make the extraordinary claim more plausible, you have to rule out the more mundane possibilities. Prove it's doing something unusual. Until then, "we can't prove it either way" doesn't mean there's a 50/50 chance.

The people fighting for those recordings at this point have seen reasonable explanations and dismissed them

It's like the Flat Earth documentary where a group crowdfunds an absurd laser and, when it demonstrates the Earth's curvature, reason that they need to "troubleshoot" that 'flawed' result.

There is always a hand to wave.

When you hear hoofbeats, think horses, not unicorns.

Unless you can't see the horses. Then think horse spirits.

Or look for a slight hill