>People are extremely likely to upload footage they think is a real UFO. There isn't a shred of physical evidence for UFOS

Is there some central repository of alleged UFO evidence that every single human with a camera is given access to as soon as they get the camera? No, I don't think that's what you meant.

There is a huge amount of human-generated information, and it is ambiguous and practically impossible to process as a whole. No one person can audit all of the videos uploaded to Youtube, rumble, odysee, etc. If we want to argue about what footage has been uploaded, we have to be able to specify what body of footage we are familiar with.

I don't know your background -- people in various walks of life have very different ways of talking about evidence. In my experience of non-paranormal claims, scholars cite scholarly sources, so when I see people saying, "There is no evidence" without immediately adding a bunch of book titles and journal articles, I suspect they are commenting outside their field of expertise.

Instead of just saying "there is no evidence," which is overly broad, you could argue, "I, <insert name here>, have confidence in experts X, Y, and Z, plus committees P, Q, and R <insert websites here> and all their reports on the evidence have been negative."