I have uploaded several videos and marked them private. They play fine when I access Youtube using my laptop etc but I cannot access them from my Samsung smart TV - which has an Internet connection or my Samsung home theater which also has internet connection. My son also has a Samsung smart tv which was able to watch private movies but recently they stopped working. In all cases the name of the video with a picture can be seen but a message is displayed something along the lines "unable to play video" and then after 5 seconds it steps on to the next video.
I have contacted Samsung tech support but they say its not their problem.
My tv uses internet@tv and the home theatre and my sons TV use smart hub
When first accessing you tube on the TV I was presented with a password to input via my laptop to a link something like youtube/authenticate and the password was accepted and signalled back to the TV. Normal public videos play fine.