All along, YouTube has maintained a policy against violent content.
Video content restrictions
If a video contains violent or graphic content that appears to be posted in a shocking, sensational, or disrespectful manner, it's less likely to be allowed on YouTube. We also don't allow content that’s intended to incite violence or encourage dangerous activities. We review content on a case by case basis and will only make limited exceptions for appropriate educational, documentary, artistic, and scientific contexts, where the purpose of posting is clear.
In light of this, we ask that uploaders post as much information as possible in the title and description of their video to help us and viewers understand the primary purpose of the video. Please note, even with this additional context, it's still not acceptable to post violent or gory content that's primarily intended to be shocking, sensational, or disrespectful and this type of content is prohibited on YouTube. Learn more here.
Actual surgical footage potentially could be considered "violent or graphic content," but YouTube typically has looked the other way given it's educational aspect... that is until now.
As public attention has turned towards YouTube and other social media platforms to be more responsible for content that is present on their sites, YouTube has started to enforce their own policies more strictly.
Although surgical videos are still allowed on its site, given it's graphic content, such videos are now being placed behind an age restriction.
What this practically means for surgeon uploaders is that these videos can no longer earn advertisement revenue, and more importantly, gets pushed down on search results behind other videos without age restrictions. As such, views typically plummet in numbers once age restriction is enforced.
HOWEVER, what is still allowed on YouTube without age restriction are animated surgical procedures.
So if a surgeon wants to upload videos educating the public on surgical procedures AND wants to get a lot of views... animation is the way to go!
Other benefits of animation include no need for patient consent, complete control over appearance, and ability to modify/change any aspect.
Check out these two videos. The first one is an animation of a Cochlear Implant without age restriction whereas YouTube enforced an age restriction on the second video (tonsillectomy).