I want to make sure I understand what you're asking here. You have a DVD player hooked up to arbitrary input 1, and a multi-dvd player hooked up to arbitrary input 2. You want to watch video from input 1 but listen to sound from input 2 (or maybe the other way around) right?

If so, and if the audio for both are connected to digital inputs, it shouldn't be a big deal to do at all. While Don Bruechert is correct that you can only use one digital input at a time for a given source, the digital inputs are all assignable. This means that you can pick the video you want and then change the audio to the digital input from the other device. I don't know how complicated or simple that is to do with the 1070, but on my 1050 I have a button that just toggles through the all of the digital inputs and then the analog input for the source I'm using. So if I'm watching TIVO on video 1 with audio coming from OPT 1, I can toggle through analog audio for video 1, OPT 1 digital in, OPT 2 digital in, and COAX digital in with the touch of a button. Simple to change my audio from OPT 1 to the CD on OPT 2.

If it's not as simple to toggle inputs on the 1070, there's another way that this can be done with my 1050 which may very well work with the 1070. If I am watching a video source, say DVD and then pick an audio only input, such as CD, the audio switches but the video remains being fed through from the previous source. So if you have an unused audio only source, perhaps the AUX input, you could assign that to the desired digital audio input. So in this example you select the video input you wish to watch and then switch to the AUX input. You now would have the video being fed through from your video source but you would also have the audio from your AUX input, which you have assigned to the other digital input of interest.