This issue has been noted for years. Video decoding can indeed work on one set and not the next. This area is well discussed with the short answer being "Encode the video in a way the TV understands." As to what that encoding is, each model varies and sometimes they don't tell. This means you have to try a few.
I have an LG 55LW5300 and LG 47LM6700 . Both are 3D TVs. I have a USB stick with some MP4 movies on it. When I plug the USB into the 6700 all the MP4 files are recognized and play fine. But, when I plug that same stick in the 5300 a few of the movies come up abnormal (red circle with x) and they wont play. I am not sure why the same video file would play fine on one LG TV and not the other one. Any input on what I need to do to fix this problem would be appreciated.