video will not show in DVD player only Audio on iMac both Play on my Air Mac

My DVD's will not show the Video, only play audio from my Super Drive on my iMac.
The Remote control for the DVD player shows and DVD Player is in then top pane.
My I hook up my Super Drive to my Air Mac both Audio and Video play in DVD Player.

When I click on the Video in the super Drive window it says :

"The Document "Video-TS.VOB could not be opened.
Quick Time Player cannot open files of this Type."

All the various Video when I click them on show the same drop down window.
I do not understand how Quick Time is being stated when it opens DVD Player.

Somehow I must have changed a setting or an update effect something.

Any Ideas on how to correct this?

Thanks

Greg