I can't find anything definite, but what I have found indicates that the USB stick would need to be formatted on a computer before using it in the video converter, so that would indicate that your PC would be able to read the files from the stick OK.
To make them into a "proper DVD" that would play on all players you'd need to convert them to the correct format (MPEG2) as MPEG4 is not a standard format for DVD players (some will play it directly, some won't) there are loads of bit's of software that will do this for you, just google MPEG4 to DVD