There should be no problems with viewing a DVD movie on the external monitor via a VGA connection.
Output the notebook screen/desktop to the external monitor after making the physical connection. Usually, right clicking on the notebook desktop will give you a menu to output the graphics to the external monitor screen. Of course, you will turn on the monitor first.
If the external monitor has speakers, your audio may be better from the monitor than from the notebook's speakers. Use a a proper cable connection from the notebook's audio out [or headphone port] to the audio in on the monitor.
An even better audio performance would be to powered speakers in an AV system.