You theory would appear to be that this would discourage violence, personally I think it would further inflame passions and desensitize folks to the suffering involved. And remember, that would go both ways - if you run the video of a Muslim being gunned down, you're going to have someone run a video of a white person being gunned down and that will be run on continuous loop at every RWNJ site on the net - "Look what they did to us - to arms, citizens!"
No, your last sentence seemed to hint a better way - video of weeping parents might touch folks who were too calloused from previous propaganda to care.
I think the most effective video we've seen in raising awareness in years was the material that came out of Florida from the Parkland kids. Scared the bejebus out of the Right for a while because they didn't pick sides or criticize individuals, but made a strong case for change. Would love to see more along those lines.