  While videoconferencing is prevalent, concurrent participation channels are
limited. People experience challenges keeping up with the discussion, and
misunderstanding frequently occurs. Through a formative study, we probed into
the design space of providing real-time transcripts as an extra communication
space for video meeting attendees. We then present MeetScript, a system that
provides parallel participation channels through real-time interactive
transcripts. MeetScript visualizes the discussion through a chat-alike
interface and allows meeting attendees to make real-time collaborative
annotations. Over time, MeetScript gradually hides extraneous content to retain
the most essential information on the transcript, with the goal of reducing the
cognitive load required on users to process the information in real time. In an
experiment with 80 users in 22 teams, we compared MeetScript with two baseline
conditions where participants used Zoom alone (business-as-usual), or Zoom with
an adds-on transcription service (Otter.ai). We found that MeetScript
significantly enhanced people's non-verbal participation and recollection of
their teams' decision-making processes compared to the baselines. Users liked
that MeetScript allowed them to easily navigate the transcript and
contextualize feedback and new ideas with existing ones.
