From technology point of view, within the STB, at some point, a
de-crypted transport streams (bits -> bytes -> packets -> frames -> HD picture) has to flow.
Transport streams for MPEG2 are will known and published in 20+ books. Not sure just how proprietory DTV's own TS is, chances are it is not very different from the standard one. There ARE differences though, and they are likely the sole reason for 169 not having DTV recording out just yet (it IS already working though, in their lab, see the _other thread
All that 16x9's modification does, is tap into this bitstream, do some massaging (TS, that is used for MPEG2 over Firewire is different from what travels inside of DTC100) and shoots it out of Firewire port.
Neither the STB, nor (naturally) DTV is aware that this stream is tapped into. I doubt that DTV can do anything to defeat this either. Simply because there HAS to be MPEG2 stream, entering the built-in MPEG2 Decoder.
I, personally, will purchase 169 gizmo as soon as they fully support DTV time-shifting.
Inasmuch as I admire 169 for realizing a business opp, going through lots of pain and technical challenges to make it reality, I have significant doubts about the whole thing.
While we have right to time-shift, I am afraid MPAA's Shuyster,Shuyster'n'Shuyster legal team will find something to blackmail any company, that dares to record-enable HD content, out of business. I hope 169 is playing it smart, so that they can keep the money they have earned, when and if the certified letter comes.
Of course

) ... if MPAA plays dirty (do they know any other way ?) there is no guarantee that the schematics won't show up on the Web . I haven't see the mod, but I'd bet half the house it is built on Xilinx FPGA along with TI's Firewire chipset - total of $60 worth of components. All one needs is a $1 tiny chip that holds the firmware... I betcha they will be 100 or so PCB houses here and in Canada, aching to sell you the PCB for $10.99. Soldering iron, flux and some solder will set you back another $8 at your local RatShack
Anyway, because of the threat, I advise quick action - as soon as DTV recording is officially announced by 169, get your module !
With Dish's marriage to DTV being on hold, we are bound to have 2-3 years of HD-recording heaven ahead of us.
For the sake of all of us - don't scream here or anywhere else about "recording HD from DTV" . Use a much more appropriate
term of "time-shifting".