It doesn't.
Most US cable boxes have firewire, which by law should be enabled, which will allow you to record over the air channels, including local HD. However if you wanted to record HD HBO, you have to spend more for some really experimental equipment. Pretty much all of the non-over air, over 100/analog, are 5C encrypted. Basically you need a HD PVR to connect to your STD's component out. If you don't have component out, then you need to get a DVI to component converter (cheap). If you only have HDMI, then you need an HDMI to component converter (not cheap, and may be blacklisted). And if you want to record two streams, you have to double all the equipment. That will get you close to functionality of the HD TiVo.
Basically if you have basic analog cable, MythTV is the way to go. If you have digital cable, with HD packages, and want non-over air HD channels, then TiVo is the way to go. That is unless you want to mess with a lot of stuff. I just wanted to watch TV.
I used to get a daily call from AT&T pushing their Uverse, DSL, etc. Even though I told them no, they would call back the next day. So my only course was to forward my land line to my Google Voice phone number to block them. Soon after that I received a postcard asking if I was having problem with my land line.
Stage 3 tarballs
When I ran Gentoo, I could do a full install in less than a half hour.
I forward my AT&T land line number to my Google Voice number in order to block the constant AT&T telemarketers that call me.
I battled with my cable company to get them to enable the firewire on my cable box. After a long battle, they did. However only the over-the-air channels were not encrypted. The rest, including the HD channels, were 5C encrypted.
Instead of playing their little game, I purchased a HD PVR from Hauppauge. It's a component (Y,Pb,Pr) input recorder. Now there is no way to block me, except by disabling the component output on the cable box.
The young lady had an unusual list, Linked in part to a structural weakness. She set no preconditions.