See. Exactly my point. I'd be on the brakes all the way down there which is why I made the statement that my descending is c**p!!
Watching Cancellara descend was awesome and I think there's a few things we can take from that video.
1, The road is clear, he can use the whole road because there should be no uphill traffic. One less thing to worry about.
2, The road is clean, swept clear of rocks and gravel. Again another thing he does have to really consider.
3, He knows the road and therefore how much speed he can bring into every corner
4, He trusts his bike, he know's his brakes work well and his tyres will hold.
Two things that have helped me in the past
1, Follow someone else who is faster. It helps me to see what can be done so I understand what I have to do.
2, Practice actually descending, how often do you just set out to ride one section of road/trail? Ride it once, go back up and see if you can go faster and repeat.
And one tip I've found useful is to move back and up a little in the saddle. Don't stand, just direct more of your weight through your pedals than your bum, especially in the corners. Really weight that outside foot. Putting more weight on your pedals than your saddle will lower your center of gravity and,I've found, make the bike feel more stable.