I wouldn’t worry about this unless it’s a game or software, and even then, the non-pirated version probably has DRM that’s somehow worse than malware.
Now if your video file ends up being a password protected rar and you don’t already know the password, just delete it and find another video torrent.
Which Linux did you install? How old is your installation? Do you have auto update enabled or do you regularly install updates?
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IDK I’d assume anything uploaded more than 10 years ago needs to be re-encoded (but you should learn more about the old and new encodings before generalizing that blindly).
I’ve also had success removing embedded language audio tracks from a file that had 5+ languages from the original Blu-ray. Each language was over 1GB/per movie for a specific offending collection.