JACK and WARREN BALDWIN, two quarrelsome young brothers, take over daily operation of Head Over Heels, a South Beach, Florida, video dating service founded by their flamboyant mother, ROXANNE.  While their sexpot mom delights in her swinging single life, her would-be Cupid sons continually misfire their arrows while at work and at play.  Jack, the much more free and easy of the Baldwin siblings, is not the best match for the matchmaking business.  He's an incorrigible womanizer who's not above hitting on the agency's clientele as they scan the lonely hearts club's video library for their soulmates.  Warren is more suited to running the business and, although salvaging personal lives is his profession, he's become hopeless and hapless ever since his wife left him for a Miami Dolphins linebacker.  Rounding out the eclectic staff at Head Over Heels is the sardonic IAN, a frustrated avant-garde filmmaker who produces each client's videotape with an exuberant, far-off flair, and VALENTINA,