Using patent language borrowed from both the Apache and GPLv3 patent clauses, in this new iteration of the patent clause we've decoupled patents from copyright, thus preserving the pure BSD nature of the copyright license. This means we are no longer creating a new open source copyright license, and the patent grant can exist on its own.
Here is the WebM license FAQ. Time to make a GPLv3 fork?
If you can't understand it, it is intuitively obvious.