Convert YouTube videos for PSP really easily
1. Get the URL of the video you want.
2. Copy URL into the "FLV Online Converter" at vixy.net
3. Choose "MP4 for iPod/PSP"
4. Wait for the conversion, download file, and then save it to your PSP under the "VIDEO" folder.
Does it get any easier than this? Not really. I found it to work quite quickly, with some impressive results.