Access checker is a feature in Gmail and Google Chat that ensures the recipients of a Drive file have permission to access it. We're now expanding Access checker to Google Slides, to make sure that anyone who is viewing or presenting a Slides presentation can play embedded videos and audio files. 

When you insert a video or audio file that is stored in Drive into Slides, Access checker will automatically look to see if the people who have access to the presentation also have access to the audio or video file you just inserted. If they don’t, Access checker will suggest changing the permissions for the audio or video file so that all viewers, commenters, editors, and owners of the presentation will be able to see and hear its content. 

We are also working toward launching functionality in the future that will perform an access check for all Drive video and audio files in the presentation after you share the presentation with additional users. At that point, we may suggest permission changes for multiple files used in the presentation. We will post any updates about this in-progress feature on the G Suite Updates Blog. 

End users 

When a user can’t play videos and audio files within a presentation, it can be disruptive. When presenting, it can be an awkward or negative experience for the presenter. However, manually checking that permissions are correct before presenting or distributing a presentation is time-consuming. By adding Access checker to Google Slides, we’re making it easier to ensure all viewers of the presentation will get a complete experience. 

Source: G Suite Updates Blog