Presently, the function BIS_fnc_playVideo does not support playing / continuing off an existing video whenever a player joins, leaving only the audio of the said video to be played. This would mean, any player joining after the video started playing would only hear the audio (from the beginning) even if the video is half way through its length with the video being blank/blackscreen.
By having the feature to configure offsets, a server check can be performed to ensure all clients (including JIP) can view the video at the exact time sequence it is being played.