This is a common tactic in Presidential debates and political maneuvering. "The Straw-Man" is also the primary tool used in debunking large scale UFO sightings and incidents, predominantly when photographic and/or video evidence is present.
Before I continue, I need to establish a key point. I am not making any claims as to what actually occurred in Belgium in 1989. There is one fact we know concerning all UFO sightings; someone reports seeing something they could not identify in the sky. I will let scientific inquiry and history be the judge of these events and their validity.
Photographic and video evidence of UFOs have only proven three things:
1) A vast number of alleged unidentified aerial phenomena caught in photographs or videos can be explained as natural or man-made; or, the quality of the images or videos are so poor that we can’t glean any useful information from them, and they are thrown out.
2) Unidentifiable aerial phenomena does occur. There are pictures and videos of lights and objects in the sky that are valid, and can not be explained at this time. The quality is good enough to make them unexplainable and there is not enough evidence to prove them to be hoaxes. Unfortunately, the pictures and videos that exist in this nebulous category are easy to recreate or have their validity questioned. Therefore, they easily become "Straw-Man" targets for debunkers regardless of whether they are real or not.
We must clearly note, however, that no photographic or video evidence exists (at least publicly) that proves, beyond the shadow of a doubt, the extraterrestrial hypothesis. People have recorded strange things in the sky; however, their origin is purely speculation.
3) Many, but not all, UFO photos and videos are intentionally hoaxed. YouTube and other similar tube sites are notoriously full of “view hungry” channels designed with this intention in mind.
The Petit-Rechain photo is a prime example of why photographic, and by extension, video evidence, will always be "The Straw-Man". When the hoaxer publicly announced that the photo was a fake, the debunkers could smell the blood in the water. This hoax was consistently and repeatedly brought up on various forums, websites and social media pages as the final nail in the coffin for the Belgian Wave. Debunkers fell into the "Straw-Man" fallacy. Photographs and videos are a prime target because there is a significant amount of media out there that is purposefully hoaxed, totally useless or easy to explain away, regardless of quality. It really does not matter if the Petit-Rechain photo is real or fake because, from an evidence standpoint, it quickly becomes invalid; replication of any photograph or video is possible, thereby “proving” that, since the images can be reproduced, they must be fake.
The argumentative fallacy that the debunkers have to answer for, however, is that one hoaxed photo does not undo the thousands of reports that were made by credible witnesses during the Belgian wave, as well as the radar evidence caught by onboard and surface radar trackers. That being said, any debunker or skeptic worth their salt must provide solid evidence that the events did not happen. The act of debunking requires just as much evidence as the act of proving.
No debunker can disprove every sighting report made, in Belgium or any major flap or UFO incident. On the flip side, no ufologist or “believer” can prove every sighting was an actual physical phenomenon, much less that it was otherworldly.
We are left with an impasse. Ufologists, UFO theorists and believers are unable to use photos or videos because they can easily be debunked, regardless of their validity or not. On the flip side, debunkers need to do more than question the validity of a photo or video, as it is a "Straw-Man"; anyone can debunk an image or images if they really wanted to. Photographic and video evidence is, in essence, useless in proving the physical reality of a UFO event. It is also useless for a debunker to attack those same images or videos, as their validity does not truly refute the events, sightings, or physical traces that exist in flaps or other major incidents.
That being said, there may be exceptions. Photographic or video evidence collected and released by the government, major government run organizations (ie: NASA) or other organizations maintained for the public good (ie: trusted news agencies) are potentially more credible than one person grabbing a snapshot of a UFO in their backyard. This can be left up for debate.
Debunkers and believers are essentially two sides of the same coin. Each is extreme in their view of the UFO phenomenon, and each must work beyond "Straw-Man" fallacies to prove their ideas, theories and claims. That being said, public opinion rests more on the side of the debunker, so their task is less arduous than the believer. The debunker can fall back on the “Oh, come on…” argument and generally rely on the social and cultural construct of “common sense” where the believer cannot.