i found this..

Some people watch their favorite movies and videos on their PSPs. How do they do, well in this tutorial I will explain.
The process of converting video formats is made very easy by a program i found that does all the leg work for you, it is called PSP VIDEO 9, and you can download it from here:
Code:
http://dw.com.com/redir?edId=3&siteId=4&oId=3000-2194_4-10779501&ontId=2194&spi=966ea284a32fe7c35d4c72556635b706&lop=link&ltype=dl_dlnow&pid=10779501&mfgId=6303380&merId=6303380&destUrl=http%3A%2F%2Fwww.download.com%2F3001-2194_4-10779502.html%3Fspi%3D966ea284a32fe7c35d4c72556635 b706%26part%3Ddl-PSPVideo9
I have copied an easy guide from their website to get you started, here it is:

Getting Started with PSP Video 9

Unfortunately, playing videos on your PSP is not as simple as just copying files to your PSP. This is due to the fact that the PSP only knows how to handle one video format (as opposed to the many PC formats like avi, mpeg, etc) and that it only plays video files that are named a certain way.
But fear not, with PSP Video 9, you can convert your PC video files in to PSP video files and copy them over to your PSP, all with a few simple mouse clicks. This page will take you through the installation of PSP Video 9 and provide links to some guides about Video/DVD to PSP conversion using PSP Video 9.

Setting Up PSP Video 9

First off, if you want to playback the videos you converted on your PC you'll need QuickTime. While this is not a requirement, it is a good idea. You can download the latest version of QuickTime from Apple's website (http://www.apple.com/quicktime/download/) (1).

http://www.pspvideo9.com/img/getstarted/started1.png

International Users: PSP Video 9 is available in many different languages and automatically installs the correct localized version of the Microsoft CLR. If your language is not supported in the install file, you MUST download the correctly localized version of the Microsoft CLR for your language. You can download it from this page (http://www.microsoft.com/downloads/details.aspx?FamilyId=262D25E3-F589-4842-8157-034D1E7CF3A3&displaylang=en) by selecting the correct languge in the "Change Language" combo box. You need to do this before you install PSP Video 9.
You should now download (http://www.pspvideo9.com/Download/) and install PSP Video 9 if you haven't done so already (2,3). The PSP Video 9 installer will check to make sure you have the Microsoft CLR installed (it is required to run PSP Video 9). If you don't, the installer will automatically download and install it on your computer. The CLR is a 23MB file, so if the installer seems to be taking a long time, please be patient and let it run its course. This is a one time download only, so those not on broadband be patient, you won't have to re-download it again even when you upgrade PSP Video 9

http://www.pspvideo9.com/img/getstarted/started2.png In order to get the videos onto your PSP you either need to connect your PSP to you PC via USB cable or insert your Memory Stick into a memory stick reader (4). If you are having trouble figuring out how to do this, please follow this simple flash tutorial (http://www.connect.com/psp/).
Before you use PSP Video 9, make sure your Memory Stick is properly formatted. For further information on how to do this with your psp, please follow this simple flash tutorial (http://www.connect.com/psp/).
The first time you run PSP Video 9 you will see this screen. Just follow the on screen instructions, PSP Video 9 will attempt to automatically setup your PSP for video.

http://www.warezscene.org//images/statusicon/wol_error.gifThis image has been resized. Click this bar to view the full image. The original image is sized 498x490.

http://www.pspvideo9.com/img/getstarted/started3.png

Converting Video

Now we are ready to convert your first video file. Click "Convert" on the menu to go to the Convert section. Next, click the "One-Click Transcode" button and select the file you want to convert. If there are no files in your queue, conversion will begin immediately, otherwise the video will be stored in your queue.

http://www.pspvideo9.com/img/getstarted/started4.png

Once the conversion is complete, click on the Copy button to go to the Copy page. On the left hand side of the copy page, you can see all the PSP video files on your PC. Select the video you just converted and click the "Copy Video to PSP" button. Now, provided you had enough free space for the file, the file should appear on the right hand side of the page meaning the file is now on your PSP.

http://www.pspvideo9.com/img/getstarted/started5.png


You're done! You should now see the video after selecting Video from the PSP Menu.