TL;DR It isn't going to get a lot better than this.
YouTube and Facebook/Instagram have perceptual hashing built during the ISIS crisis to deal with this and teams looking.
1) What amount of video is ok for reporting purposes? This seems to be one of the questions from last night, where excerpts of the video were allowed and also included in legitimate media footage (most of that seems to be over).
The answer is: less than you think.