Many thanks to Dorota for flagging this one up. It's a (primarily) US site but don't let the accents put you off using the videos as the resources themselves make up for that (to us UK English people) in spades! There is, in fact, a 'see Britain' section where a number of the voices have British English accents (e.g. http://www.englishcentral.com/video/16402/freedom-of-speech).
As this screenshot shows you have a video (choice of thousands) which is labelled by approximate level. You watch and listen and can click on any word as you go for a definition. There are then 'learn', 'speak' and 'quiz' sections on each as follow up. Each one is a lesson in itself and could be used whole group or individually if chosen carefully by the teacher. There's a mobile version and a history of videos watched which would be useful for students who want to track their progress. The premium version gives you unlimited access and allows for course and class creation and management. I wasn't able to see what the limits were on the free account but Dorota says she has been using for a while with no issues.
For teachers there are some case studies of how it can be used like this one