First, you've probably heard Breitbart died; the 'progressives' are behaving about like you'd expect. 'Respectful dialogue' my ass.
“Many officers are also uncomfortable that their activities might be displayed on the Internet and otherwise widely distributed,” says Portland, Ore., lawyer Bert P. Krages, who specializes in the area. “Some also have the impression that photography presents a security risk and are acting according to a post-9/11 mentality.”
Adds Krages: “Law enforcement personnel are still grappling with the idea that ordinary citizens have the right to take images, whereas previously such photographs and videos were taken by professionals employed by traditional media companies.”
Well, some more "No, you DON"T have qualified immunity for this" rulings and the subsequent lawsuits would probably help get the idea across.
It would also help if they started reminding cops, from the academy on, of that Constitution thingy that has a place in their oath; and a good course on Peel's Principles would probably help, too.