Drop PSPREZ is a GUI companion for the commandline tools, PSPREZ. It alters the headers of an MPEG-4 file to fool the PSP into thinking that it is a 320x240 QVGA resolution movie. This allows playback of nonstandard resolutions from the memory stick.
In order to get Drop PSPREZ work, you have to install PSPREZ and put it into a command searching path (e.g. /usr/local/bin as suggested) due to licensing issue. You may consult the readme file for details.