Easy.

Change the way progress work in dungeons -and this is for all, not just these dungeons-

In GW2 no one can move if someone was watching cutscenes cause the next areas only oppend after all players watched or skiped them. Just that simple. In FFXIV it goes the otherway arround and is terrible, players wanting to watch cutscenes many times are leaved behind or out of bossfights which is ridiculous.