Thanks for sharing this with us.
I guess you've got to hear the good from the bad.
What I can suggest is to KEEP the player for the time being but asking the question about Flash Games for that player on their
MP4Nation's FORUM instead. It's quite active as well and will have people there who may have the same player (being a forum for MP4Nation), so hopefully you may get a better answer than one from their Customer Service.
If not, maybe someone here on MyMPx.org can help. I don't have your player unfortunately so I can't really help but will try.
Do you have a SAMPLE GAME on the player? Maybe the game needs to be copied into a particular folder? What's the error message you get when trying to play the Flash game? If you can post the problem in a new thread, that would be great and hopefully other members who see it who may have the same (or similar) player can help out...