As it stands, we aren't setting out any hard and fast rules for how the memories are experienced by the spectators. Mu is a strange, fluxing place, so experiences can vary.

Characters "telling the story" - the ones whose memories are being played out - are not required to exist simultaneously outside the memories as they happen, but if you'd like to go that route, you're welcome to! This allows for both uninterrupted visualization of the memory in question as well as the potential for discussion on the side.

The only hard boundary is that the memories themselves cannot be altered.