When does the timeline stop?

Hi all,

I would need to know how to create a trigger that clicks at a certain point when the timeline is paused. Let me explain: in some slides I have videos loaded with iframe (therefore not embedded) and the subsequent slides blocked exactly the time of the video. If I open a new Chrome tab the timeline stops but the video continues to go. If I could link the playback of the video with the timeline(with js code i can do it but i don't know how to trigger it) I would then be able to unlock it only when it has finished playing the video.

Also I would like to know what are the cases in which the timeline stops?

Thanks for the help