AVS Video Editor, from which one vep file types originates uses .vep files to store projects, work in progress. The program itself supports export to several multimedia formats (including MPEG-4 video), however you will need the original multimedia data loaded along the projects.
A .vep file alone is useless, because it does only contain settings and changes done, but not the actual multimedia content.
This means that your only hope to convert vep to mp4 would be to use the AVS Video Editor and have the original video data referenced by the .vep project.
Updated: April 11, 2017