Your placeholder image is by default the first frame of your video. However, this is often an unusable image to be displayed as the placeholder. Luckily you can easily select or upload your own placeholder by following these simple steps:
Step1: Insert your video
Go to insert > video > video from file
Step2: Add the placeholder from your computer or select a frame of the video as a placeholder.
Add a placeholder from your computer:
Select the video file in your PowerPoint > press format > poster frame > Image from File > image on this computer > select your image and press ok.
Select a frame of the video as a placeholder:
Play the video in PowerPoint and pauze on the frame that you want to make the placeholder from > Select the video file in your PowerPoint > press format > poster frame > current Frame