SVCD, or Super Video CD is a way of storing a video on a CD in a similar way to storing it on a DVD. It is (of course) generally lower quality than a DVD due to the smaller size of a CD rather than a DVD.
SVCDs often do not work in VLC Player. VLC can sometimes play SVCDs using libcdio and libvcdinfo - the features page has more details. For a complete VCD/SVCD which includes menu selections, hot spots and playback control, see xine.