Earlier quoted context omitted.
That's the entire point. The crypto is not very good. Also it doesn't apply to all bluetooth keyboards because Microsoft uses a proprietary protocol to communicate apparently (at least this series of keyboards).
This is very specifically for Microsoft keyboards. There's multiple bugs that are exploited (both in the $1 receiver chip he's using and the fact that all MS keyboards start with the same bit for their mac address) that make it very easy in that specific case. Hold my beer while I perform a table flip and throw away all my Microsoft Wireless Keyboards
The only wireless keyboard I use is for my HTPC... Interesting, and somewhat scary thing. Thinking it would be easy enough to plant other electronics (surveillance devices) in such a thing.