How do you access the laptop DVD? Directly double click or other ways?
Could you please try "mount" in the command line to see the output if there is a dvd mounted.
For libdvdread4, if you are sure the name is right, please use which to check the command full path like:
And execute the full path if it is a binary file.
Well, if you want to see a movie, you may as well download some good video player like VLC to play the video.