Yeah, VLC can play a wide variety of video types without external codecs. It can also capture video.
Best if you open any problematic files in MediaInfo, which will tell you precisely what you're dealing with:
I have the LG 65LW6500 myself. It's limited in which codecs are supported. It also may not recognize a particular container. For example, mine will recognize H.264 (AVC) and AC3/DTS in MKV container or TS (transport stream). It will not recognize m2ts files, even when the contents are identical to a TS or MKV. If you want to have subtitles recognized, best to use srt.
So I edit and render my captures as TS, my Blu-Ray rips as MKV. Changing an m2ts file to another container may be as simple as remuxing to TS with tsMuxer, or use something like mkvMerge for an MKV.
But you first have to know what you're dealing with.