Its capable, but that also requires a BETTER video card to run it. If you tried something similar to a machine such as the macbook, macbook air, mac mini, it'll lag if they used the GPU for those features. Therefore, it relies on a seperate component to do the SAME THING without requiring maxed out specs on the VIDEO CARD or CPU.
Well, OS X actually is NOT capable of this feature.
Neither are the GMA 950 or GMA X3100s used in the Mac minis and MacBooks.
However, all of the dedicated GPUs Apple has been using for the last few generations of computers have been. Even the old Radeon 9200 used in the now old iBook G4s and Mac minis were capable of full MPEG-2 decoding and deblocking. But OS X does not take advantage of these features.
Also, those features don't require "maxed out specs". Nvidia and ATI/AMD's GPUs have been doing things like this for generations now, and even their integrated GPUs have had similar capabilities for quite some time.
The lowest models of the GeForce 8400M family can even have these features, and be configured with only 64MB of video memory if Apple chooses to do so.
The thing is, even modern low-end hardware is capable of features beyond what Apple includes in their "low-end" hardware that has a premium price.
Thats why its possible for low-end PC hardware well under $1,000 to be able to play blu-ray and HD DVD discs, as well as modern games.
I'm not saying Macs are better then PCs because PCs usually have the upper hand when it comes to upgrade/repair. However, OSX is far superior to Windows Vista or XP in many different ways that we don't use normally so we don't notice it. Its just the little things that people tend not to even bother mentioning and just go ahead with the major stuff such as GUI or bundled programs.
OS X being "superior" to Windows is also a matter of opinion. While OS X might have the advantage in say... UI or the way you install software, Windows is far more flexible and has better software variety and DirectX gaming walks all over what OS X can do with OpenGL. Also, OS X has no equivalent to software like WinDVD, PowerDVD, Media Center (Vista), and Nero.
Furthermore, unless your watching a blue-ray or HD-DVD movie on a HDTV with an HDMI thats connected to your laptop, people can easily say that default DVD player program that came with OSX are more then enough in terms of picture quality and sound quality.
Spoken like someone who has never used a good DVD player in Windows with a good GPU
Tiger and below had DVD Players that were just terrible. Not even worth mentioning. But Leopard's is better. However, it is still a night and day difference comparing it to WinDVD, PowerDVD, or Vista's built-in decoder. Especially if your hardware is doing all of the work as far as deinterlacing, deblocking, etc. is concerned. When it comes to audio, there is no comparison. You get boomy and funky sounding bass with DVD Player in OS X, thanks to the EQ and the LFE channel (the .1 in 5.1) being discarded. WinDVD and others in Windows can decode the LFE and send it through to headphones or speakers. That makes the difference between boomy bad sounding bass and a good set of headphones hitting as low as a subwoofer and vibrating on your head
For the most part, OS X vs. Windows is subjective. There are areas where both have advantages over others. It really depends on what you're willing to sacrifice. With OS X you have to sacrifice video quality, gaming, software choice, and (lately) hardware build quality, but you gain great built-in software and a beautiful UI and some really cool features. With Windows you have to sacrifice a great pack-in software package and a much better UI, but you gain better hardware, better video, and more overall flexibility.
