Don't pay for Windows antivirus apps. It comes with it's own.

None of it is any better than Defender. When Defender came on the scene, every enterprise I've worked in stopped buying AV licenses - they have that little value.

Video and audio are unlikely to contain a virus that Defender wouldn't catch (say an executable renamed as an mp3) which just wouldn't launch anyway.

The one thing you can do to improve your security is to stop running as admin on Windows (which the first user account is by default and necessity). Create a user account just for doing this stuff - a regular user account, which means it can't make changes to the system itself.

Even better is to test anything suspicious in a VM.

Using Linux for this is the best approach all around. Get an old laptop, run Linux. Most tools are developed for Linux first anyway.