MatCat:
That defeats my purpose, what are the commercial units doing that I can't do?
No offence, but I haven't a clue what you can do or not do in the way of video design and construction projects, as I can only judge you on the questions you have asked so far. But I do see a price effective proven commercial solution there that you might want to consider. I buy lots of prebuilt modules and shields that I could probably build myself but looking at it figure I couldn't match the price + time consumed Vs other things I could be designing and building.
Good luck;
Lefty