That is not actually the case. Youtube has a concept of both private and unlisted videos. Unlisted videos work similarly to how you describe Megaupload:
"Unlisted videos
Making a video unlisted means that only people who have the link to the video can view it. To share an unlisted video, just share the link with the people who you’d like to have access to it, and they’ll then be able to see it. Unlike private videos, the people you share the video with do not need to have a Google account to see the video, and they can share with more people simply by forwarding the link to them.
Unlisted videos won’t appear in any of YouTube's public spaces, like your channel page or search results."
Ok, put another way... all videos on Youtube are videos and relatively transparent, easy to view and inspect. On a file locker your files are opaque mysterious entities that the site can't hope to inspect.
Not to incriminate myself or anything, but I have been given copyrighted documents with Google Drive. (Though I've ingested many orders of magnitude more copyrighted documents through youtube...)
That is not actually the case. Youtube has a concept of both private and unlisted videos. Unlisted videos work similarly to how you describe Megaupload:
"Unlisted videos
Making a video unlisted means that only people who have the link to the video can view it. To share an unlisted video, just share the link with the people who you’d like to have access to it, and they’ll then be able to see it. Unlike private videos, the people you share the video with do not need to have a Google account to see the video, and they can share with more people simply by forwarding the link to them.
Unlisted videos won’t appear in any of YouTube's public spaces, like your channel page or search results."
https://support.google.com/youtube/answer/157177?hl=en