Why do two identical files have the same working and non-working file sizes bit by bit?

Question

Data recovery

I restored 4 video files from the memory card from non-working files, copying their name and finding them on YouTube, downloaded them again, eventually noticed one oddity for some reason 4 non-working files together had a size of 744235618 bytes and those 4 videos that I re-downloaded from YouTube had the same size of 744235618 bytes, provided that I downloaded these videos in FHD resolution from the same site.

Question: Why non-working videos have the same size in bytes as working ones?

Answer 1

how to make a non-working file of the same size from a working file?
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flip random bits!

Answer 2

because the size of the files is not damaged.