Panasonic ST30 series Media Player

I just had my 60ST30 delivered and it's great. I've been trying to get various video files to play through the Media player by way of a thumb drive. I've only had success with some .mkv files. I've tried various files with no luck. I've tried creating my own .mkv files with no luck. I believe there is an issue with the audio track but I can't figure out the right configuration. Has anyone had success with playing video through the media player? If so, what is the file format?

Thanks in advance...