These were big in the late 90s going into the early 00s. And there were also SVCDs which were MPEG2 video insead of MPEG1. There were a few brands of DVD players that supported them, APEX was the 90s one form China and then Phillips had some models that played lots of formats including avi files. The avi files often used a testing mpg4 video codec in the microsoft video player that got extracted and became the standard and grew into Divx and later Xvid.