Q: Can you make copies of DVD

Yes.   Please read this support article:

https://support.apple.com/kb/PH5846?locale=en_US

Ciao.

How to copy previously-burned DVD-R video discs

http://support.apple.com/kb/HT2059

To create an image file, launch Disk Utility and select File: New: Disk Image From Folder. In the window that appears, navigate to the desired folder and then click on Image. Give the image file a name, and click on Save when prompted. That’s it.

Or, if you have Roxio Toast, just use the copy function.

Note that this only applies to homemade videos - if you are referring to a commercial disk, the built in copyright/DRM protection will not allow your computer or Roxio Toast to copy it.