I was sort of hoping for another in-depth interview, but was disappointed to see that this was a video. For highly technical information, video is way too low-bandwidth a medium for my tastes; I prefer to read. Oh well.
Have you tried watching sped up video? I've started doing that recently and like it quite a bit.
Does Facebook (his employer) use D internally for anything?
Possibly, there are Thrift bindings for D.
However I suspect Alexei was hired more for his elite C++ chops than his Damascene conversion.
Bit of a stretch to call it a "conversion". He and Walter Bright simply set out to fix the glaring problems with C++ after long experience with it.
I must have the wrong version of the story. My understanding is that WB wrote D and AA came later (and wrote the book).
That is correct as far as I know, but not a fine enough granularity. Walter Bright designed and implemented D. That version is commonly called D1. Andrei Alexandrescu, however, worked with Walter Bright on the design of D2, which is now what most people mean when they say "D".