Be aware that the Dish EHD works differently than D*s.
It is for MOVING recordings to it from the receiver drive, and vice versa. You can not record directly to it (the either or principle) like D*. Unlike D* if you have any other VIP series DVR (622/722/722K), you can move the drive among them. And, it needs a USB drive.
the EXT setting is for recording to the pocketdish not an Hdd.