Sure, we can have tools to reduce risk - maybe there can be a warning under the video that the contents are disputed and some people claimed harm. If those people are lying the video uploader can sue them.
Just because some people don't know how to behave and have delusions that nothing is real on the internet, we can't have total speech control in an attempt of "saving the kids".
Just as with the real world, people need to develop the right habits to stay safe.