This is a bad solution, in fact it is the absolute wrong solution. If for some reason, like you sell your MBP and want to take the data doubler out to use it in another laptop, the reverse issue will happen and the drive will again not be recognised. this is what you shoudl have done (I posted this solution before on 1-11-2013, see above)
I had the same issue after I installed an OWC data Doubler with a large hard drive in my MBP, and installed the Superdrive in an external enclosure.
This is not a hardware issue! It's a function of how the OS is set up to recognise the drive as an "internal" drive, as specified in the system file "DVDPlayback"
This is what I did to solve this issue.
Download and install VLC player. http://www.videolan.org/vlc/index.html
Go to System Preferences/CDs & DVDs
Under "When you insert a video DVD" click on the dialog box.
Choose "Open other application ..."
Choose VLC
Done!
This is such a simple solution, and what is great, it can easily be reversed if the data doubler is removed.