Is there a feature within After Effects that would allow me to search through video using facial detection functionality? Something similar to AMD's Content Manager seen in this article? It would be super helpful to have for my old videos.
There is no facial recognition in After Effects or any plug-ins that will do it. You will have to use some other software.
I am sure that in CC 2015 Adobe has implemented facial detection and tracking.
Facial DETECTION however is in premier pro (from my sources)
You can track a face but you cannot do facia recognition. Facial recognition can pick out Bob from the video, face tracking will find the eyes mouth and nose. Facial recognition would need to runwithout user input and After Effects requires user input to do anything.