If you like using YouTube videos in your educational presentations but hate all the excess (comments, links to other questionable videos, visual clutter etc.) you will be excited to learn about Safe ShareTV.
Safe ShareTV allows you to share your video without all the extra distractions, PLUS you can even crop the video to show only the part that you want to.
Click on this link to see a video on the solar system.
You may also want to consider Quietube, although my preference is Safe ShareTV for ease of use.