For those of us who buy used videos, it's not a pretty picture. DVDs are taking over, and many films are slipping through the cracks, unlikely to ever come out on the imposing new format. There are few places you can even find used videos for sale. Incidentally, by "used videos" -- euphemistically called "previewed" sometimes -- we don't mean those ubiquitous tapes sold in bulk after they hit (or miss) the theaters. No, we refer to those little out-of-the-way flicks your Blockbuster clerk swears, on the movie The Bible, do not exist. It must be the blue dye from the uniform soaking into his or her head, because the Record Exchange is proof positive these movies are still playing somewhere. Still. At Record Exchange, you'll find movie history captured on tape. You'll find common titles, obscure titles, films with subtitles, British horror, Disney comedy. You'll wonder how there was ever enough time in the world to make all these movies, or little enough money, and how David Carradine could star in so many and still be one person. Whether or not past flick owners were kind and took the time to rewind isn't pertinent -- just read the ingredients: "stylish, sexy thriller!, " "the feel-good movie of the century" or "from the director of Porky's 3!" The Record Exchange makes its new home in a former public library, a structure whose vintage modernism could be South St. Louis' entry in Futureland. Inside, used records seem to grow out of the floor. And the videos grow out of a need for film fans to see -- and buy -- what they've been missing. The ghost of the library haunts the Record Exchange, but the requisite whispers have been replaced by lead vocals. That's right -- as you shop, you'll be serenaded by an actual turntable. Librarily speaking, were the books better than the movies? Something tells me the radical film (and music) buffs who shop at the Record Exchange have burned their library cards.