Desktop manager is a free app that can be downloaded from the BlackBerry site. If you do not have this downloaded to the computer that you sync your BlackBerry with now would be a good time to download and install it.
Step 1. Connect your BlackBerry to the computer with desktop manager installed.
Step 2. Open BlackBerry desktop manager by finding the icon on the desktop or in the programs menu on your computer. Select “Media” from the menu and click on “launch”.
Step 3. Locate the video files on the left hand side of the screen and choose the file you want to convert. Click on the video file you want to convert and hold the mouse button down. Now drag this file to the lower right side of the screen which represents the files on your BlackBerry Curve. As Media Manager copies the file it can also convert the file into a format the BlackBerry can use, such as an AVI or MOV file. A dialog box will open and ask what you want to do, choose "convert for optimal playback" and It will also resize the video to fit on the screen of your BlackBerry Curve.
Step 4. Repeat step 3 for each video file you want to convert onto your BlackBerry Curve.