Videos from a free online service should only be used if you have a reasonable belief that they were uploaded legally. A good way to check this is to look at what account posted the video. For example, if the official account for BBC News or the producer of a documentary uploaded content, the content is more likely to be a legal copy. If an individual account uploads a copy of a full-length feature film, it is likely not a legal copy. More information about asessing the legality of content can be found in FAQ 1.15. If you are reasonably certain that the video on the service is a legal copy, then displaying that video in your class or linking to it for teaching purposes is permitted, as long as it is played from the service directly and not copied or downloaded.