Without hijacking the thread, in my quest to get the Humax to play native AAC from Get Iplayer, if you copy over from the Humax a bog standard MP4 file saved by the custom software you would expect to see it via pressing the Media button as a video or does this only support a limited set of file types and MP4 isn't one. I know I should probably know the answer but I'll claim age, since it covers a lot.
I did copy an MP4a file from Get Iplayer onto the Humax hard drive renaming to MP4 and it does play, but sounds a bit twangy (distorted) although that could be the source. Bringing it over via the Humax iPlayer it does sound the same. So question is how do you get the Humax to see MP4 files over a network ?.
The other check is whether the Humax can handle the high bit rates that are used on R3 - perhaps they are one of the same between sources. Haven't checked that.