The question I would ask is, if there are claimed civilian sightings of these things somewhere pretty much every day, why is the video quality always so poor?
1. you have the Mitch Hedburg explanation. “I think Bigfoot is blurry, that's the problem. It's not the photographer's fault. Bigfoot is blurry, and that's extra scary to me. There's a large, out-of-focus monster roaming the countryside. ” change big foot for aliens.
1b. the non-joke version is that IF you believe these ships are capable of FTL and thus capable of things our understanding of science can't explain, why would you expect our current scientific tools (or cameras) to be able to fully capture them in focus?
2. similar to 1b, If they are interdimensional, they may not be fully in this dimension and thus the fuzzyness is due to that.
3. people make crappy witnesses, makes sense they are also crappy photographers.
4. the good videos are getting deleted. we already know the government is in our phones, wouldn't be too much for them to control the data exported from them or how they are saved. this makes sense because we know from these hearings the government is actively covering up what we actually know.
5. some sort of stealth technology, that may have some warm up/cool down period after they do something, so they are only visible for short times. could also be temporary/partial failures that make them blurry when visible.
6. we only believe we actually know where/what/how close these objects are when we see them. They could be a lot further away than we think. would explain why we don't hear them, or see immediate results of their passing. some type of forced perspective/optical illusion.
7. it could be a low-tech, but still outside our realm of knowledge, explanation. like some sort of paint, coating or material, that disperse light in a way that makes them seem blurry. we have things like Vanta-black, and radar-reflective paints, so a "blurry" coating isn't very far fetched.