The best stories across the web on media and technology, curated by Leandro Oliva.

1. How does Wikipedia deal with a mass shooting? (Nieman Lab)

2. Fox’s bloody t-shirt: Newtown images show risks of automated ads (paidContent)

3. Facebook prepares to bring video ads to news feed, aims for TV dollars (Ad Age)

4. Am I the product? users react to Instagram’s terms of service shift (GigaOM)

5. With Nielsen Deal, can Arbitron step into the digital age? (PandoDaily)