They plotted to take over the world, but now they can't even be found on DVD. Such is the plight of Pinky and the Brain. The maniacal lab mice, once tops in Toontown, are now just video toast. Sure, we can watch episodes on VHS, but think how gratifying it would be to see ''Mouse of La Mancha'' packaged with extras. ''The outtakes are just spectacular,'' says Rob Paulsen (the voice of Pinky), who describes the improv-heavy recording sessions as ''hugely entertaining.'' That's enough to make us salivate. Yet Warner Home Video (owned by EW parent Time Warner) tells us that there are no plans for a DVD release at this time. ''Maybe this article will spark some interest,'' muses Paulsen. To which we add an enthusiastic ''Narf!''