Next-gen HD-DVD discs are protected using HDCP and AACS. HDCP is an authentication standard that is built into hardware, whereas AACS is the encryption that works with the actual movie file. If you can decrypt the movie and render it out for MPEG2, HDCP becomes redundant.

Muslix achieved this with a fairly sophisticated hack just before Christmas.

Now, Blu-ray uses the exact same approach - HDCP for the auth and AACS for the crypto. By altering the HD-DVD crack to take account the slightly different file structure and crypto key standards in Blu-ray, he has achieved the same thing - decrypting Blu-ray movies out to plain old MPEG2