For the newer Philips DVD players, most mass storage devices are accepted as long as they are formatted to FAT16 or FAT32. Your proposed drive is a 320 GB so should be all right if formatted to FAT32.
In the manual it states that the DVP5982 will only recognise a limited number of folders and files, so look at that in case it would be a problem.
Playback could raise some issues because it doesn’t say whether the player’s USB socket is USB 2.0 or 1.1. The latter would probably be OK for XviD/DivX files but MPEG2 might not work properly.