How to Modify Videos in PowerPoint
After inserting a video file, there are various options you can modify, including the video appearance, size, playback, and start and end points.
The Adjust group of the Format tab contains all the options you’ll need to modify the video’s appearance.
If the video isn't quite the right size, you can change that too, just like you would a picture.
The Trim Video option allows you to cut off portions of the beginning or end of a video to make it shorter.
You can either type specific values into the Start Time and End Time fields or click and drag the start and end handles in the timeline below the video.