Update: I haven't found video or slides about Rian Hunter's explanation, but I did find this note about his CUSEC 2012 talk:
At the Dropbox talk, Rian Hunter explained how Dropbox was able to integrate into the Mac OS X finder and the hoops that they had to jump through to implement this feature. The technical aspects of the talk were centered on how the engineers used very low level C code to trick the operating system into thinking that the Dropbox client was a part of the finder when it actually was not. An unexpected but enjoyable surprise was the presence of an Apple engineer who worked on the OS X operating system. It was almost if trying to break the software was a game of cat and mouse between Apple and Dropbox, but in the end, both Rian and the engineer created an extremely informative and enjoyable discussion.
https://www.quora.com/Many-articles-about-Drew-Houston-say-t...
Update: I haven't found video or slides about Rian Hunter's explanation, but I did find this note about his CUSEC 2012 talk:
At the Dropbox talk, Rian Hunter explained how Dropbox was able to integrate into the Mac OS X finder and the hoops that they had to jump through to implement this feature. The technical aspects of the talk were centered on how the engineers used very low level C code to trick the operating system into thinking that the Dropbox client was a part of the finder when it actually was not. An unexpected but enjoyable surprise was the presence of an Apple engineer who worked on the OS X operating system. It was almost if trying to break the software was a game of cat and mouse between Apple and Dropbox, but in the end, both Rian and the engineer created an extremely informative and enjoyable discussion.
-- http://iwarrior.uwaterloo.ca/2012/02/01/13721/softies-invade...