How to insert videos in Google Slides from Google Drive
INSERT A VIDEO INTO SLIDES
1. Open your Google Slides
2. Click File
3. Insert
4. Video
5. From Drive
6. Select and insert your video
7. Resize and move video within the slide
CHECK SHARED PERMISSIONS
8. Go to drive.google.com
9. Find and right-click on the video
10. Select Share
11. Below Restricted, select Change Link
12. Use the pull-down menu to choose "Anyone with the link"
13. Done