Broadcast political media is becoming more social. Technology has advanced to the point where now many online video “livestreams” come with embedded livestreaming chatboxes, uniting the on-screen and social components into one realtime, integrated experience. We investigate how these chatboxes may shape perceptions of political events. We conducted a field experiment during the September 2019 Democratic Primary Debate where subjects were assigned to view the debate with or without streaming chatboxes. Subjects were encouraged to view the debate on the ABC homepage (with no chatbox), on FiveThirtyEight.com (expert chat) or on Facebook (social chat). We use text analysis to characterize the types of comments in the two chat streams. Our experimental findings indicate that Democratic subjects assigned to the Facebook chat condition reported lower affect towards Democrats and a worse viewing experience. The tone of candidate-directed comments also matter: We find that the number of negative comments about a candidate on the social chat predicts a decreased feeling thermometer rating of that candidate, while the number of positive comments predicts increased belief that that candidate will improve in the polls.