if I have multiple video actors in a stage running in the background, that I have activated through the "activate scene"-actor, is there then a way to controll that scene, concretely when the videos start if I am running a show in another scene?

 Yes.

FILE DOWNLOAD: https://www.dropbox.com/scl/fo/hx3x0pq568up5muyekw8o/h?rlkey=rxqp3wxznkcprjveetmx07hvj&dl=0

"Control" Scene

Background Scene

So, my question is, if I have multiple video actors in a stage running in the background, that I have activated through the "activate scene"-actor, is there then a way to controll that scene, concretely when the videos start if I am running a show in another scene?
I can try and post an example.

Here's a revised version that incorporates restarting videos at the start of crossfades: https://www.dropbox.com/scl/fi/zgbnwx2x07tvqepq370oi/Virtual-Stage-Crossfades-v2-2024-03-14-3.2.6.zip?rlkey=rcaqgtwtksevbk2d2wv9h031y&dl=0

Also this file of mine shows a few different ways to do crossfades with video that you might be able to recycle: https://troikatronix.com/add-ons/random-media-random-duration/

Not entirely sure I understand what you are trying to do based on your description, but hopefully one of these three crossfade methods will be useful to you. 

FILE DOWNLOAD