It is my understanding that the "PocketDish" is an orphan. Abandoned by Dish/Echostar, all support, such as there is, comes from Archos. Since the PocketDish went out of production quite some time ago, and that price seems high for an old used PocketDish, I assume you are actually referring to an Archos model.
You might get SD versions out of the HD recordings, but that's about it. Viewing is not restricted to the built in screen. I wanted to buy the new HD Archos models (which are NOT PocketDish products) and use them to take my Dish HD recordings to my RV and play them on my HDTV there. No dice. No such plug-in is available. Nor, sadly, does it look like there will be now.
They're leaving money on the table. I guess not enough for the two companies to bother picking up. Frankly, I see little other use for Archos, other than for playing Dish HD programs moved over to it. Sure, you could save OTA and play it. Why bother? I'd think that would have to be a smaller market than the Dish market (which could include OTA recordings to Dish HD DVRs).
There is a plug-in (Model 700162WEB), but I gather it does not support Dish HD recordings.