The Purdue OWL site has excellent help for writing.
US National Library of Medicine
Teens Health (not the same as Teen Health and Wellness database)
Also: Do a Google search for a foundation or other site devoted to your topic. (Ex. American Heart Association, American Cancer Society)
www.ytcropper.com Works in all browsers.
Paste a Youtube URL in ytcropper. Select the clip you want to save. Click Crop and copy the URL.
Insert the URL into the slide. You may insert a picture and embed the link for a better design.