Being new, I was thrilled to FINALLY burn a video file onto my dvd. However, when I tried to add a second video to the dvd, the error message came up "must use blank media. You can only burn video files to blank media". What?! Isn't that the purpose of using a dvd+rw, so I can add to my dvd? The files I'm using are not big. I'm at a loss! thanks for any advice.