Well it played nicely with H264-encoded videos generated a year ago. What would be useful to me is for you to generate one with the latest version of VP since I can't. That way I could see if the latest VP H264 encoder "plays nicely" with the MED800X3D.
Tried all 4 combinations. None play video on my player although audio plays. 60fps variable results in "unsupported format" on both my PC (using VLC) and my player. 30fps plays on my PC and results in "video unknown" on my player. I have lots of videos generated in 2017 and early 2018 with VideoPad using H264 encoding with various output settings that play on my player. Something changed after that.
Here's the link to my project files. I exported both mp4 and an avi H264 versions. The avi one plays correctly on my MED800X3D, the mp4 does not (blank scrren). Both play OK on my PC.
https://www.dropbox.com/s/geu26nrln8yirhk/testH264.zip?dl=0
MP4s created using H264 encoding results in a blank screen during play on my MED800X3D multimedia player. MP4s from other editors and cameras (e.g., GoPro) play just fine. Output settings are 1280x720, 29.97 fps.