FrenchUser,
that is the best beer I have been sent.
The reason it is 1GB is because it was a hacked chip, these players can only support a maximum 2GB nand Flash Memory. Killing your player , formatting and reflashing has removed the hack and the chips true size is now shown.
To confirm this you can check the serial number of the memory chip against this list
HERE
Now what problems are you having with video?
What size is your player screen?
What version of MP3 Player Utilities are you using?