It depends on what you mean by "host". If you copy material from website A to website B, that would be copyright infringement when done without permission. However, you can post the URL to a website (not effective if it's behind a paywall, for example Netflix): a URL is not copyright-protected (it's a "fact", not an expression). Nevertheless, the website that actually holds the movie may have terms of service that limit what you can do with their content, so you'd have to comply with those terms for any content originating from such a site.
There are myriad thousands of illegally-uploaded and distributed videos. The primary explanation for that is the contempt or ignorance that people have regarding the law. For instance, it is widely believed that you can upload material if it's for your use of that of friends, or if you don't make any money off of it, or it's not currently available online elsewhere, or if paying costs too much, or thousands of other excuses – none of which makes copyright infringement legal. The other factor is that there are 10 billion web pages, and it is impossible to effectively play enforcement whack-a-mole with infringers. In addition, actual enforcement can be a challenge if the website is in a non-cooperative jurisdiction.
