There is considerable variation in the ability to descent in the senior peloton, and I don't think it is correlated with age; some people just are better at the subtle work, such as recovering from a wheel slipping away, and some have more brute power.
For example, the ability to bunny hop varies. http://www.cxmagazine.com/to-hop-or-not-bunny-hopping-cycloc... claims that, in Sven Nijs's case, it is to do with his BMX experience.
I couldn't find a good video from cycle-cross, but here is a nice example from road racing: https://www.youtube.com/watch?v=iPHnqI13vPk. Not everybody is as willing to take those risks and as good in recovering from (for him) minor mishaps as Vincenzo Nibali. Some cyclists are even known to take in a few bisons of water at tops of mountains because heavier bikes descend faster.