After import PDF files or images, click the Edit button to open Page Editor Window.
Click and draw a rectangle on the flip pge you want to add YouTube video to, and you will see a video player appears. Open the video in browser and copy the video ID and paste to below YouTube Video ID area. You can customzie the video palyer appearance, add poster image or set the video auto start when reader flips to this page or play in loops.
Click File - Save and Exit.