I looked at the 3 Windows 7 machines I have and not one does this recording. And here the cable/uverse/other tv systems block content recording so what could be recorded is almost nothing.
-> Good question but for now you may want to post this as a "feature request." And put it to Microsoft to support DLNA natively.
You give us network connectivity, you use words "Recorded TV", point us to LAN connected computers and then you do not support .wtv format!? "Recoded TV" on Windows 7 IS in .wtv format! Anyone home? What is the point of the whole excercise? I just downloaded the latest firmware 3003 - the same thing.
Not A Happy Bunny