Instructions
Connect your PSP to your PC with the PSP's USB cable. Click the "USB Connection" option in the PSP system menu.
Open iTunes on your computer, then click the "Movies" tab.
Right-click the movie you want transferred to your PSP, then click "Get Info." Make note of the path next to the "Where" field in the window that appears.
Click "Start," then enter the path found next to the "Where" field in the text box that appears.
Click "Start" again, then click "Computer." Double-click the PSP icon in the window that appears.
Click and drag the movie to the "Movies" file in the PSP.