Why do some parents trust their parents over their own child? (Serious question)(?)

Edited (Top Half, original question below):
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Just take the video as it is. I think it wasn’t the best idea to ask the question in here as I was informed and saw.

I am seeing people answering honestly about what they think and they are being downvoted for their opinion. I didn’t mean to subjugate anyone to that and it hurts/feels bad.

Just upvoted, I guess, if you feel the video is cringe and the father is a PoS. I understand people care about karma and I am warning that answering the question honestly may cause a dip. I’ll ask the question in another subreddit but keep the video up because I hate this interaction and it makes me cringe, but also question.

P.S.: I am not, and will not be, downvoting anyone.

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Original Message:
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I’m autistic, so I sometimes struggle understanding certain family/social dynamics or want to understand them better, and I’m genuinely trying to learn from people who are more knowledgeable or who have professional or lived experience with this topic.

I recently saw this video where a father seemed unwilling to believe his daughter’s accusation against her grandfather, especially because she disclosed it much later. Part of me wonders whether he truly trusts his father, is in denial, or simply doesn’t want to accept the possibility.

During Mental Health First Aid training, I was taught that it’s important to take disclosures seriously and support the person coming forward rather than immediately dismissing them, because not being believed can cause additional trauma, isolation, or prevent future reporting.

My question is: psychologically or socially, why do some parents side with their own parents over their child in situations like this?

Does having a much longer relationship/history with their parents make it harder to accept the possibility that abuse happened? Do some parents feel their parents “could never do that”? Does denial become a coping mechanism because accepting it would completely change how they view their family and childhood?

Also, can ordinary childhood lying (small things like denying they took food or broke something) unfairly affect how seriously later disclosures are treated? Could familiarity with typical childhood dishonesty, or even projecting their own experiences as a child, make some parents instinctively trust their own parent more?

I’d especially appreciate insight from therapists, social workers, psychologists, advocates, or people with relevant experience. I’m trying to better understand the family dynamics and psychology behind these reactions.

I strongly support Take Back the Night and have heard similar stories from survivors speaking publicly about relatives or parents refusing to believe them, sometimes even leading to estrangement or disownment.

I’m posting this here because I found the video disturbing/cringe, but also because I’m hoping people who understand these dynamics better might be willing to explain them. So… half posting a video and half asking what many of you all think, your own perspectives.