Having survived a ’50s outlaw-biker stigma and ’60s financial troubles, Harley-Davidson’s gentle glide into the ’90s slow lane of mainstream respectability is commemorated by a reverential documentary, Harley-Davidson: The American Motorcycle originally broadcast on TBS. Adding a half hour of material not shown on TV, the video tribute includes clips from such diverse Harley-hogging movies as the Marx Brothers’ Duck Soup, Kenneth Anger’s Scorpio Rising, the Three Stooges’ Playing the Ponies, and a 1980 sci-fi spoof, Galaxina, in which rocket-jockey cultists worship at a cycle-toppped altar. A