Porn Vids is a subreddit that describes itself as being 'a NSFW community for sharing porn and sex videos'. It claims to be a lot better than many other places owing to the fact that it has active moderation to get rid of spam, corporate submissions and vote rigging - three things that the Reddit community really isn't a fan of.
Note that /r/PornVids has a pretty strict system of uploading videos that includes listing the length of the scene as well as tags to assist in working out what type of content there is. While Reddit is the worst type of platform for tube-style sharing, this place does a pretty good job given what the layout of Reddit provides.
There are just over 117,000 readers and new submissions are made about 10 times a day. Like all of Reddit, you can go through the material and upvote or downvote what you think is of a decent quality.