The newer DVD players play just about every media format out there. You'll have to look in the manual or look up the model specs on line. I watch a lot of media files and about one in ten I'll see a message "File Not Supported"
is your usb drive formatted for FAT32? over 4gb it's almost likely formatted for ntfs which it won't recognize.
plus it depends on the video codec too. some won't recognize xvid and some won't recognize divx.
your best bet would be to take these videos, find yourself a converter program like ConvertXToDVD and drag/drop them into there and burn them to a blank disc.
torrent the program. it's up on pirate bay and it's a great program.