Roy and Carol Williams have owned a video rental business for more than two decades, and in that time they have dealt with a flood of competitors most of which have since closed their doors the inception of Netflix and a storm of $1 movie rental kiosks.Despite an always challenging landscape in which to make a buck, Williams and a small handful other video rental retailers have managed to hang on where others failed by offering low-priced movie rentals or by renting and selling niche movies, such as Spanish-language or pornographic videos.Williams' small 600-square-foot store on Lemmon Valley Drive is …