Title: Play a video automatically in a slide show - PowerPoint
Headings: Play a video automatically in a slide show
Play a video automatically in a slide show
Play a video automatically when a slide appears in Slide Show
Another option: Play in Click Sequence

Content: Play a video automatically in a slide show - PowerPoint
Play a video automatically in a slide show
PowerPoint for Microsoft 365 PowerPoint 2019 PowerPoint 2016 PowerPoint 2013
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When you’re delivering your presentation, you may want a video to play automatically as soon as the slide it's on appears onscreen. Play a video automatically when a slide appears in Slide Show
In Normal view, click the video in your slide. Under Video Tools, click the Playback tab. Next to Start, click the down arrow, and select Automatically. When you are delivering your presentation in Slide Show View or Presenter View, the video will play automatically when you arrive at the slide. If your slide doesn’t have a video in it yet, you can add one. Go to Add and play a video in a presentation for more information. Important: Certain older video file formats may not compress or export properly in Office on a Windows RT PC. Instead, use modern media formats such as H.264 and Advanced Audio Coding (AAC), which PowerPoint 2013 RT supports.