A supplement is shared together with the demo it supplements

When a task has a demo and then a short follow-up clip that only supplements it, the shared demo page now shows both: the original demo on top and the follow-up below it as an addendum, under one link. Before, sharing or approving the follow-up published it on its own, so colleagues never saw the change it supplements. Before the first share, the share box says which earlier demo goes along. A demo recorded afresh still takes the place of the one before.