Tried but couldn't find an answer to this exact question. Here's the situation: I created a movie project in iMovie, then burned it to a DVD using iDVD. The burned DVD plays in my iMac but will not play in a DVD player. I get a Cannot play this type of disk error message. I used a DVD-R disk (Memorex). I can provide more information if needed to figure this out, but is there a simple answer as to why this would happen? The DVD player says it plays DVD-R disks. The disk works in my computer. Any ideas from the experts?