Imac Apple TV app not playing my home videos.

Ok, here's some more subtlety to the situation. I find that if I try to add an m4v file then nothing happens. If I then change the filename extension to mp4, then the file is added to the TV app library. This seems pretty consistent. However if ask the TV app to show me duplicate items, everyone of those added in this way has a duplicate entry. One shows a little tiny video screen next the entry and one does not. But both point to the same file on the hard drive (with the mp4 appendage). And they only show as duplicates by making that selection in the file menu. So I then tried making the mp4 change and dragging the file in without having failed with the m4v. Then nothing happens. However, if I change it back to the original m4v and then drag it in, it then is successfully added to the library. There is something strange afoot here in Apple's programing of the TV app. Switching to mov appendage also works but again requires dragging twice (with different appendage) before it enters the library. They all appear to go into 'Home Videos' as you would expect.

Ok, thanks for replying but you have totally missed my point. I have followed all the instructions. I'm a Mac user since 1984. The current Mac TV app does not allow me to import existing video files from my hard drive into the Apple TV library. It doesn't matter whether I drag them in or use File Import. Nothing happens. It will take home videos as from Photos but it will not take any of the hundreds of mp4 or m4v files I have made from DVDs over the years. iTunes had no problem importing these files but when they split the TV app off from iTunes it lost functionality. As near as I can tell many people have had this problem (https://forums.macrumors.com/threads/ripped-dvd-library-no-longer-showing-up-on-apple-tv-app.2301753/) and have turned to Infuse or similar apps to make up for what Apple should be providing to simply use existing video files.