TV Article MTV UNPLUGGED By EW Staff Published on January 19, 1996 05:00AM EST MTV UNPLUGGED (Viacom New Media, CD-ROM for PC and Mac, $19.99) The way Alex Coletti keeps popping up on this disc and crowing about the show he produces, you’d think he invented the acoustic guitar. After all, it’s just a cable-TV concert program. Still, the show is superior to this disc, on which you access ”All Access” and get people talking about.set building. Is this MTV or Home Improvement? Click on a star’s picture in ”The Vault” and watch choppy 30-second video clips of such acts as Nirvana and Paul Simon (there are only three full songs on the entire disc). You get one feeling after fooling around with this CD-ROM, and it’s not pleasure, it’s frustration. C-