To document with videos is valuable, but I think the site should provide as much context as possible, what I would wish for, show:
* Date of incident
* Short description of context
* Primary source, or at least, where the video was found
* Media coverage of incident
* Updates on convictions/official investigations into the incident
* Official statements / responses
* linked videos (videos of the same incident, but with other view-angle)
Otherwise it will just be a collection of outrage, if you don't give real data to put things into context.
edit: formatting