Just bought a Samsung 43" Class J5200 Full LED Smart TV. Mfg date is Sept 2018. Dropped Sony Vue because there was no App for the Samsung. Went with YouTube TV because app was available for Smart TV's mfg'd after 2016. After setting up noticed YTV app was not appearing for download so had to really dig. Found this little gem. ↓↓↓↓ Cant handle YouTube TV! Needed new tv for meeting room so hopefully TV can handle a Powerpoint presentation when plugged into a laptop so I can salvage some value.
The J series was designed prior to this. It was YouTube's decision to end flash based applications.
You can reach out to Youtube regarding televisions that support YouTube TV.
The date can be determined by the letter in your model code "UN" stands for LED TV The next set of numbers "43" stands for the size of the television and the the next letter determines the year the unit came out in. However this is normally Samsung proprietary information. You can research your model online and it will advise you of the year on Samsung.com.