Scott Janousek give a good tips on loading external video.
1. Depending on your setup (device, network, etc) ... try using: rtsp:// instead of http:// to target the clip. 2. Make sure the target clip is encoded correctly (by testing it on the target device). Test with the actual video device player to be sure. 3. Use a getURL to target the 3gp clip ... see if the device video player can render it. 4. Also make sure the dimensions of the video match those set on your stage proportionally. 5. Make sure the video clip on the stage has an instance name assigned to target ... in your case: my_video.