The problem with taking anything from the military at face value is that secrecy and deception are part of their job description. That includes some branches of the military not telling other branches everything, and conducting tests on troops without telling them. The secrecy means we can't know the capabilities and limitations of the hardware used to take the videos, radar images or whatever else they provide, so can't be definitive on whether other explanations like the Mick West ones fit. We can't be sure of what other aircraft were in the area at the time because something trying to be stealthy isn't going to be visible in public records, whether it's friendly or not. We can't be sure that some branch of the military doesn't know what it is, either because it's one of theirs, or because they don't want the enemy to know they know about it. And we can't be sure they haven't cooked up a convincing fake as cover for something secret. Plus because the military isn't monolithic more than one of these can be true at the same time - the part releasing the video may truly not know what it is while some other part does, but isn't telling anyone, and a third part is using it as cover for something else.
This also comes back to the earlier points on disclosure to congress or the public - there is an inherent tension between the need for military to keep some things absolutely secret and the need for effective oversight. If it gets out that you can intercept and decrypt enemy communications they'll change something and you'll be back to square one - it's a necessary secret that you go to extreme lengths to protect (Operation Mincemeat etc.) On the other hand if it's something the enemy knows, or that you need them to know (a deterrent is only a deterrent if the other side knows about it!) then there's no problem making it public. And a whole sliding scale in between, with specific information varying with threat level.
The way this usually works is that some subset of people that are trusted by both military and non-military get given the oversight task and can be trusted to keep the secrets. It only works when there's trust from both sides, and no part of either side is playing the system. At various times there have been politicians the military does not trust with secrets, either because they are suspect themselves or because someone close to them is, personally or professionally. Equally from time to time some part of the military is less than forthcoming about something that doesn't need to be secret because it's something they shouldn't have been doing (Oliver North?) or because it's just embarrassing. Politicians demanding an answer in a public session that they know can't be given because it's a secret would be another example - the person being questioned is caught between opposing obligations, to keep the matter secret but not to mislead congress for example. It gets tricky when it's something that the military thinks should be secret, but civilians think they have a right to know...
