: It is well-known that the US theatrical version (2006) cut the original bleak ending found in the UK release. The 2007 BluRay releases generally restored this "original" ending, which is widely considered the superior, more haunting conclusion to Sarah’s journey.
: The video compression codec used to keep the file size manageable while maintaining high quality.
This isn’t an official "Best Buy" edition. In release naming, “best” typically means the encoder selected the highest-quality settings for the x264 encode, possibly including: