Guessing your already aware that you can use your computer such as a laptop as a portable DVD player.
I bought a portable DVD player years ago for long trips to keep my daughter busy with learning shows vs vegging in the back seat. Other than that I havent found any other use for my portable DVD player. I play my DVD movies on my bluray player connected to TV or just play them through teh DVD ROM drive on my computers.
Most of the portable DVD player functions are pretty basic. Play, Play Backwards, Fast Forward, and DVD menu selection buttons.
Are you going to be plugging this into a larger display or using the small display that comes with the portable DVD player?