Medical videos are videos of parts of the human body. Usually for education and training. All videos can be used for personal (offline) projects for friends and family. Usually restrictions apply for businesses and published (online) projects like blogs. Read each web site's "copyright notice" or "user agreement" before using.
Endoscopy Learning Center
"The documents within the GASTROLAB Home Page WWW pages are here for informational and educational purposes only."
GE Scientific Movie Library
I didn't find copyright information on this site BUT I suspect it's free for personal use because they've made downloadable formats.
Centers for Disease Control: Public Health Image L
"Most of the images (and videos) in the collection are in the public domain and are thus free of any copyright restrictions. If you look directly beneath the image you will see a fair use statement that tells you if the image is public domain or copyright protected. Permission is not required for public domain images, but we do ask that you credit the original institution and contributor, when known, whenever the image is used in any publicly distributed media. If the image is copyright protected, you will have to contact the content provider to obtain usage permission."