uh Apple
I remember back in days it was the ONLY way to buy Digital Video and back then all you needed was iTunes 10 + Requiem, was free and easy! Do you want the bad news or good news first? I;'ll start with Good since I am having a bad day and could use some Good news
What currently works (going by my set up):
iTunes 12.6.5.3 (x64): that's if you want to be able to access Japanese store, you could go a little higher. Not sure what it is.
TunesKit M4V Converter: You can't even buy it anymore, since it's Abandonware you maybe able to hunt down a copy on the net w/ a key. As the above post mention DRmare may work just as well.
Some newer movies cannot be downloaded w/ older iTunes (new releases like Super Mario Bros or GI Origins) and thus cannot be fully decrypted. The work around is download them w/ latest version but you can only decrypt 720 (1080 will not play at all). (VMware comes in handy here)
You need to uninstall and stay away from the latest iTunes and downgrade to at least the one I have. I know newer ones work but no idea where that limit is and locked out of Japanese store if you even care about that.
Also none of these programs are able to losslessly remove AAC audio for some reason and it's re-encoded (check the size in Media Info) but that's pretty minor since it's low quality anyway. Video, AC3 (if present) and Subs are all good.
BAD NEWS:
Apple is canceling iTunes, it's been long gone from the Mac since Mohave. It is being replaced w/ AppleTV+ App which you can actually download it from Windows store now.
The biggest issue w/ AppleTV+ app is Apple also decided to get rid of the m4v files, and replace them w/ a new format. They are HLS encrypted into MOVPKG package. Zero support for this DRM, and those files are limited to the app (itunes won't play them) and all you can do is limited air-play. Really stupid!
So it's time limited. Better get them decrypted now before the whole entire windows closes.
Though there is hope someone will crack the new DRM at some point.