YouTube.com has a strongly enforced policy against sexual content, but some interesting videos can slip through the cracks. One classification is instructional videos, such as on male genital shaving, medical examinations, putting on a condom, or penis enlargement techniques. Yes, you can see actual erections on YouTube.
Another classification that passes YouTube is artistic works, such as dances, photography collections, kinetic art, even if the subjects appear nude.
Far too many videos are uploaded for YouTube personnel to approve each one. Therefore, anyone can upload any video, but if members of the the public complain, it will be taken down. You can sometimes see some before anyone flags them by entering a search term and then click the Filters button and then Upload Date.
You might enjoy this video, which has been on YouTube for quite a while: Do a search for “What is ED 15.”
Full masturbating and ejaculating scene, as well as some female nudity
Intimate Massage starts at about 1:23:00
Brother and Sister Naked Body Painting
Body Painted Males, Some with Erections