Some external DVD drives will work with Chromebooks. The one that has been recommended by Google is the ASUS CD-DVD Replacement Drive for Chromecast (sold on Amazon).
External DVD drives are not officially supported, but it looks like this particular model works. You can also try using something like Kies Air to connect your Android phone wirelessly with your Chromebook so you can use the phone’s screen as a display and install two google drive apps – android remote desktop and air DVD player which you run together on both devices so the wireless signal gets sent back and forth up to our 30 feet away without lag.