Joining a game or a demo in the middle of the game/broadcast is made a bit difficult because if one goes back to move 1 and starts going forward. He won’t see the kibitz “appear” as it did on the real game/demo. KGS does it like this and it’s very nice to be able to follow the kibitz while also following the game when not spectating it “live”.
Only thing needed would be that the kibitz/chat area would scroll in tandem with the moves. I go to move 1 and the chat would automatically scroll to that point in time. Then it would just follow the moves.
This one was suggested during 2014 Finnish Championship Second Qualifiers.