Niall Ferguson: USA could collapse. What about UK?

In the video below Prof Niall Ferguson of Harvard University is explaining why the US could collapse under the weight of debt it has. The collapse he argues would be akin to the collapse of the Soviet Union which buckled under the weight of the Afghanistan war.

Given that the UK has bought $250m of US debt. Some argue that this is a currency where the US and UK print new money and buy each other's debt to make themselves look solvent.

All this raises the question that if the US could well collapse then isn't the UK in exactly the same postion? And if a Harvard professor is talking about the US becoming a failed state then why does the US have AAA ratings? Are the ratings agencies captured?

All this is should say one things to Scots. Demand powers of your taxes and prepare for a new currency!