Yes, but check the web site on which you found it for sharing permissions first, and be aware that sometimes videos are being made available on the Internet illegally. Usually when that happens the copyright holder eventually notices and asks to have the video removed from the web site. Then the link will no longer work.
Some legal and free services that offer a great deal of streaming content and make their money from advertising are:
One place where you can find out which streaming services carry a particular film or documentaries is: