You're thinking of CD+Gs. The "G" is for graphics. Basically the CD plays while very slowly updating, low quality graphics appear on the screen. These CD+Gs were also playable on the Sega CD (which came with a CD+G sampler), the Saturn, and probably some other systems.
You can still buy CD+Gs, but they are all for karaoke nowadays. I think the best theoretical use for them is opera (because of the subtitles you can put at the bottom), and some of these were produced, but I never had one, and basically the format is dead for anything other than karaoke now, as far as I know.
I have...one CD+G, I think. Its the CD Single for "Fly the Sky", the opening theme of G Gundam. The graphics are less than impressive.
Probably one of the best CD+Gs easily availible in the US is the first album from Information Society. I bought it on vinyl, but I have watched the CD+G all the way through. I'm not sure if newer pressings of this CD still have the "+G" parts though.