[Stooky Bill]

If theyre struggling with HD sources how are the monitor walls powered?

You mean the ones on sets? Good question, presumably they're seperate from the main video router and gallery systems. 

As I say they've been handling HD in some situations for years, but on stand alone systems and clever ways of getting the video out of the building. Down the line cameras in some regions and the programme edit suites have been HD long before the news production part was. It could be done because they didn't rely on the main video router. 

Though there was a system  called Dirac that allowed the BBC to pass HD video on an uncompressed SD video signal. This was used a lot to get HD from SD facilities over SD only circuits