Video Format, but excellent. He interviews employees at Youtube, Twitter & Facebook who discuss steps they are taking to counter bots, hacked accounts and other spam efforts.
Youtube:
https://www.youtube.com/watch?v=1PGm8LslEb4
Twitter:
https://www.youtube.com/watch?v=V-1RhQ1uuQ4
Facebook:
https://www.youtube.com/watch?v=FY_NtO7SIrY