I thought the same thing but somewhat changed my mind. I realized that a bunch of the people wandering around the capital may not have had their phones on them so the FIB wouldn't necessarily have cell ping proof they were there. Some were probably young and tech-aware while some were old and likely afraid they would have their phones stolen in a mugging.

Either way there were probably hundreds that were not carrying phones that could be tracked. Releasing the video would be proof of those people being there.

I'm not fully convinced on this being a bad thing or a good thing so I'm watching it for a few days to see what happens as a result. Since it involves CONgress it is probably bad by default, but we will all see fairly quickly anyway. Someone will spill the beans somewhere.