Signed-in attendees can use the thumbs-up button while viewing a talk in its broadcast or video view. Each attendee can have one active vote for a talk; selecting the button again removes that vote.
See the results
In your event dashboard, go to Content & Schedule > Reports > Sessions. The talk list shows the current vote total, and you can export the report when you need the data outside HeySummit.
Votes in event emails
HeySummit's daily digest can highlight up to three top-voted talks from the previous day. Whether that section appears depends on the event's email configuration and whether eligible talks received votes.
The vote button is part of the current broadcast or video talk view and there is no event-level dashboard setting to turn it off.