There are three videos of interest, imo. What is called the "gimbal" video, what is called the "tic tac" video, and what is called the "go fast" video. The one you are discussing here is the so-called gimbal footage. I strongly suspect that what you are calling insect legs are in fact asymmetrical artefacts of the infrared tracking. It is clear from watching the video that the object rotates independently of the aircraft's attitude.
The gimbal video is not of the Nimitz incident, which is the "tic tac" event. As I said above, for that event, objects were radar observed by the USS Princeton intermittently for a two week period prior to this sortie. During the sortie, commander David Fravor had prolonged visual contact with the object as did his accompanying aircraft. They did not succeed in getting a tracking capture. A subsequent aircraft launch after Fravor had landed captured the tracking video.
I am no UFO nut, but I'm also no debunker. This cannot be an insect/insects if these military people aren't lying. It also cannot be a conventional aircraft because of its behavior. This then leads to the following possibility set, imo:
1) High capability technology of our (human) own, perhaps being (surreptitiously) tested to determine real world pilot response (but that's a bit of a conspiracy theory and not very plausible, imo)
2) A natural phenomenon of this world of a form we don't understand (the most likely, imo)
3) Technology or phenomena associated with a source that is not human and not from here
4) Carefully contrived hoax with military involvement and consent (again, has the "conspiracy theory" problem).