DVD Player with ability to add scrolling messages?

A friend of mine is going to open a gym and wants to have a LCD on the wall playing dvd’s etc thru a PC sat in the office. What he would also like is the ability to have customised scrolling messages displayed along the bottom of the display whilst playing the dvd’s.

Does anyone know of any such software available?

Hell, i’d even consider a DivX player with scrolling message option, but a DVD player would be my first choice. To save me converting everything to DivX.

Thanks for your help