I struggle a bit with big online events, they are designed to be as interactive as possible but it is very rarely done in a way that comes even close to actually being anything like a normal interaction.
In the case of the Earth Day Live stream, the interactivity was via the live chat box next to the video on YouTube, and with a big number of people messaging at it, and a lot of them just being spammy or uninteresting (to me) comments, it is virtually impossible to have any kind of conversation with any other individual or small group.
I don't know what the answer to that is maybe it is, as @Skylar suggested, to have 'watch parties' for these kind of things with a smaller number of people involved and a dedicated forum or chat for them to talk about it and interact.
