The decoders in these Smart TVs are not as good as your PC. I don't want to repeat that discussion but will share I've had some luck with HANDBRAKE. And again, sorry but this is not an offer to write any tutorial on HANDBRAKE.

There's another issue looming and there is no fix. Some models stop playing and 2 hours and some number of minutes. Some think this is to curb the play of pirated movies.