At last video indexing is possible with www.viewdle.com. I am sure you will be amazed when you will visit the site. It can recognize a person in real-time from a video. You can search a person video & can view how many times he/she appears on screen. 
In the site it says:
Viewdle is a video indexing and reference system that fuses pioneering, facial-recognition visual analysis technology along with other leading search techniques to automatically look “inside the video” and identify true on-screen appearances with unrivaled accuracy and relevance. Viewdle’s frame-by-frame analysis provides search results based upon the actual video assets, not just the associated metadata. Viewdle solves the inefficiencies inherent in using text-based metadata and other existing tools for indexing, searching and retrieving moving media.
For example to see real-time face recognition of Benazir Bhutto visit this link & click a video link: Benazir Bhutto
Following image describes how the system works to index & recognize a person from a video:
