No it will not play because on webOS, forced TV mode on it's OS prvents mxplayer from playing. This cannot be changed unless you jailbreak OS.
I was planning to buy a new smart TV of a higher screen size and I have decided I will not buy LG or Samsung that have proprietary OS like webOS or Tizen. VU would be good idea and I will examine the OS of other brands too. No more buying TV's with proprietary OS. This is the 2nd time I am moving away from LG. Earlier I junked their Washing machine as their franchisee service centres are frauds and change even good parts. and the washing machine was tearing clothes.