The above link states one output and that it can received DISH HD but not Direct TV HD but they are working on it.
If you look at the thread, in "Let Us Entertain You," you will see several references of how systems are hooked up.
I have 2 Sat receivers with dual input here at the stick house. I have dish network. I have one dish antenna. One lead feeds the dual inputs on one receiver, and the other lead feeds the dual inputs on the other receiver. (722 and 322 models but I'll check for sure if you are interested) Dish provides the splitters and combiners for the single lead into the dual inputs. I have 4 televisions in the stick house and all four receive independently their own channel to view. (Remember, only two receivers)
When we travel, I take the 722 with me. It is a DVR and I'll record some movies before we depart for those rainy nights. You will loose signal when it is raining. With the DVR in the Hanna, I watch TV in the living room, OR a different channel in the bedroom. See the article in "Let Us Entertain You," on this subject. I'm to lazy to search for the link.
Based on the article in the link above, the antenna does matter in viewing HDTV. Based in an article that I posted in another link, if your outside antenna can received UHF channels, you can receive DIGITAL TV SIGNALS.(That is not HD) So the VuCube will receive digital tv and HD for DISH signals, but not HD for Direct TV. Most likely it has to do with the band pass/stop filters in the VuCube.