Viz Communications, Inc. is ending its video distribution relationship with Pioneer Entertainment, effective March 1, in favor of Ventura Distribution, Inc.  Ventura also distributes titles by anime producers Central Park Media, Media Blaster, and Tokyopop to the video trade.  The Viz deal with Ventura is for three years.  In addition to its own titles, Pioneer also distributes Bandai Entertainment titles to video stores.  A Pioneer spokesperson declined to comment on the situation.