Mr. Bill's 20th Anniversary

What Art Clokey's Gumby is to Play-Doh innocence, Walter Williams' Mr. Bill is to harsh playground reality: In short after hilarious short on the old Saturday Night Live, the squeaky-voiced Mr. Bill was set upon, set aflame, jailed, melted, and otherwise discombobulated by the inescapable Sluggo and the Kafkaesque Mr. Hands. There's new mayhem in Mr. Bill's 20th Anniversary, a video anthology which includes an amusing short called ''Mr. Bill Goes to Washington'' — but it's the old, grainy films from the Saturday Night Live days that prompt genuine sick chuckles. Guess they don't maim hapless clayboys like they used to. B-