Stable release is targeted at most users. Start with her. It contains four launchers: 1080 Main, 1080 Advanced, 4K Basic and 4K Advanced. They differ in performance on a particular device. Try successively one by one until you find one that works best for you. Also, 4K launchers support QHD and UHD resolutions.
Smart YouTube apk is the output engines. Used in 1080 and 4K alt versions. Download them only if the application itself is not able to deliver them.
Standard installation via ADB
If you don’t know how to sideload/install apps via ADB, read a tutorial (e.g. this one) Download latest SmartYouTubeTV APK and sideload/install with adb: adb install -r SmartYouTubeTV_Orig.apk Enjoy