To ensure the video is ready to go for your presentations, the best approach is:
by putting the video on four slides within one deck.
This method allows for a seamless transition, ensuring that the video can be easily played during each presentation without needing to manage multiple copies or slideshows. If you want the video to start automatically whenever you reach that slide, you can also select the “Play automatically” option, but having the video on each slide is the main requirement for it to be available for each presentation.