Judging from his feedback that people have left no one has complained that the 4GB mp4 players are hacked or anything. Normally I think atleast one person would have noticed this. However the only problem people seem to be having with him are that he either ships them very late or sends them the wrong colour. Other then that I don't see any signs of bad players. Only way to find out is try them and format them with the guide available on this website. Heres the link:
http://www.mympxplayer.org/how-to-re...ck-vt2400.html
p.s. It is possible for the mp4 players to have 2x2GB memory cards in them aswell, anything above 4GB seems unlikely to be legit.