Project Veritas videos on 2016 election interference. "Bird-dog" is a plant sent to a rally to create bad press. An example is the Donald Duck costumes Hillary had sent to Trump.
https://www.breitbart.com/politics/2016/10/17/exclusive-okeefe-video-sting-exposes-bird-dogging-democrats-effort-to-incite-violence-at-trump-rallies/