The general way YouTube works is a registered user uploads a video to be viewed, liked, disliked, commented on, and shared by other users.
To view videos on YouTube all a person needs are a connection to the internet. They are not required to register to simply watch videos.
To post videos on YouTube a person must be a registered user. When a registered user uploads a video, they are agreeing to the Terms of Service and Community Guidelines of YouTube.
While retaining all ownership rights, when a user uploads their content to YouTube, they are granting YouTube the right to use, reproduce, distribute, and display the content in any media formats and channels. YouTube does not have these rights in regard to removed or deleted content.
YouTube allows mov, mpeg4, mp4, avi, wmv, mpegps, flv, 3gpp, and webm file formats.
YouTube plays videos in flv, mp4, and webm formats.
YouTube players are controlled through an I-Frame.
You can embed the YouTube video player into a page using an I-Frame.