Disc-overed by coincidence

Instead of listening music by bluetooth from my iphone, I put in a CD in my carplayer. At least I thought it was a CD. It was not, it turned out to be a DVD and to my surprise it started to play the DVD on the display of my navigation. Wow! I didn't know that was even possible!!
Cool! 

A few moments later another surprise when I discovered that the video playback automatically stops when driving over 8 mph. (20km/u)
Audio continues though.
What a pity. Understandable of course, it's all about safety, but still....

Anyone out there knows a workaround? hehe...