It seems like PSP movies are selling much worse than it has been believed.
In a recent article from Home Media Retailing, they are reporting that "disappointing sales have slowed the flow of movies on the proprietary Universal Media Disc (UMD) to a mere trickle. At least two major studios have completely stopped releasing movies on UMD, while others are either toying with the idea or drastically cutting back."
There is even talk that Wal-Mart is considering dumping PSP movies entirely. In addition to this Universal, Paramount and Image Entertainment have also stopped creating UMD content.