Channels receivable by FireWire in Las Vegas, NV
In Las Vegas, Cox supplies FireWire-equipped Scientific Atlanta Explorer 3250HD cable boxes to customers who want HD service. Local HDTV channels (in the 730s) are available unencrypted over FireWire, in accordance with FCC regulations.
In the year since I put up this page, Cox appears to have opened up its network substantially. As far as I can tell, all of the channels to which I am subscribed (digital cable with HD, no pay-TV channels) are available, unencrypted, over FireWire—all analog-cable channels (which are now getting sent digitally as well), all digital-cable channels, all HD channels (not just locals, but national HD channels such as Discovery HD and Universal HD...Battlestar Galactica in HD will rawk :-) ). Maybe this doesn't apply to movies-on-demand (which are difficult or impossible to schedule with MythTV anyway) or to channels such as HBO and Showtime; I don't subscribe to those, so I can't test them.
I've noticed that MythTV captures from the cable box more reliably if you tell the backend that the box is an SA4250HD instead of an SA3250HD. You'll still want to use the sa3250ch channel-changer, as the internal channel changer doesn't appear to work. You should use Subversion build 14893 or later (either trunk or 0.20-fixes) to get the version that works with the cable boxes Cox issues, and invoke it with the -s option.