Have you ever come across these problems? When you add your video (mp4 format) to PSP, there are still no video files in PSP, or show you that the videos are corrupt, why? Oh, many factors will lead to this situation, maybe you can't connect your PSP correctly or you don't name video files following correct ways, anyhow it's a nuisance, here I sum up an universal way to name video and then copy video to PSP.

If your PSP firmware version is below V3.0, just follow these steps:
 1) create a folder named "MP_ROOT" in PSP memory stick
2) inside that folder create an "100MNV01" folder, and a "100ANV01" folder.
3) If your video is MP4 format, rename it with this format "M4VXXXXX.MP4", rename the thumbnail with this format "M4VXXXXX.THM", XXXXX are five random numbers you like.
4) If your video is MP4, save it in the "100MNV01" folder, but if it's AVC video, save it in the "100ANV01" folder.
But If your PSP firmware version is above V3.0, there is a little difference
 1) Create a folder named "MP_ROOT" in PSP memory stick
2) Inside that folder create a "Video" folder
3) Then copy your MP4 file to this folder

Now you may make clear something about this naming rule, but I think it seems a little complicated, isn't it? here an easy way will be shown for you.
In fact there is a totally freeware called PSP Video Manager you can download to help you to save video to PSP or export PSP MPEG4 videos located in your PSP to your computer directly and you don't need to manually rename PSP MPEG4 files, besides it support all PSP firmware versions. in a word, you can make things convenient in four instances using free PSP video manager:
1. Transfer MPEG4 format videos and movies to PSP.
2. Backup video in PSP to PC.
3. Copy PSP videos to new computer or notebook.
4. Share your PSP videos with friends.

Weather you use the universal way or the easy way, both are feasible If you want to know more about this freeware and Video DVD on PSP, you can go to this site--DVD Video Studio