There is an easy fix to this BS. Just do nothing but video. Every speaker is in a conference room with the moderator and questions come in via phone or video.
No hecklers.
Do it like a TimPool podcast.
Speakers get paid on basis of how many folks connect to see/hear the event. Just like a video by Hulu/Amazon/etc.
Do this a few times and the venues that depend upon live people on stage in front of an actual crowd will hire the security to maintain order. Someone makes a fuss — toss their ass out to the cheers of the crowd and yah get an extra video as entertainment.