I've done this with BLT, it is annoying but,
Download a video, whichever video you want. Next, Get a video converting freeware, just search on google and you should find one. And convert the video to MP3!!!!
Hook up your PSP and your computer should make a noise, or say found new hardware or something. Then, open up 'My Computer' from the start menu. It should say Removable Disk F, Or Removable Disk H, or even PSP, it will only say those things if teh PSP is hooked up via USB. Click on w/e it says, and if it says Music, Video, Games, and stuff like that, you clicked on the right thing.
Now, take the video that you converted to MP3 using the video converting software, and drag it into the VIDEO folder.
Voila, you've done it,