How can it be a “WVGA… 1080p” screen? Those are two very different things.
Maybe upscaling?
It probably has only an 800x480 LCD, which could make “1080p Screen” sound precariously close to false advertising. Still, given the price point one couldn’t really expect more.
Specifications found elsewhere (including official page retrieved using the wayback machine) indicate the screen resolution as 800x480 with the ability to handle playback of 1080p video files from usb.