Can you try downloading the samples from here -->
Sample Videos and try them on your player?
It's very unusual of an ACTIONS chipset player to have a 1.8" player that plays .MTV now a days as the upgrade .AMV video format came into player around the 1.5" screen and above players. I have old 1.2" LCD screen players that play .MTV format.
Have you also checked what's on your CD as well?
Have you tried contacting the seller about it? The MTV Convert Tool I have might be too old and might not be compatible with your player that's all so hence the "format error" as perhaps it's not in the correct format or screen resolution for your player.