Blu-Ray is a patented technology so it requires codecs (as you surmised) to be purchased (you may not have known that part).
Check this link:
To play a Blu-ray Disc, you need to use a non-Microsoft program that supports Blu-ray playback and a device capable of reading Blu-ray Discs.
Might read this too:
If this isn’t working, you can get a free player with Blu-ray compatibility for Windows 7 by visiting the website: http://download.cnet.com/Macgo-Windows-Blu-ray-Player/3000-13632_4-75453680.html