LG Prada KE850 "mp4 vedio" Questions

i cant open my videos on my lg prada ke850 phone it say path/ffl/documents/does not exists! the vedio has to be mp4 or 3gp format

...of video file i can watch on rocker E6? is there any download available to watch ".dat" format videos? you can watch video in mp4, mpeg and 3gp formats in E6. Vedio convertor can change the