Iím making a music video from clips I downloaded from the net. Some have no problem being edited, but most will either go completely black with only the sound running in the background and others will be very choppy including the sound. The sound from the videoclips is not important to me because I will be exclusively using music. How do I get this video? Is there a way for me to put it in another format? Like quick time? It seems to never have a problem being edited.