YouTube has some excellent videos which can be used for teaching.
I have a slight concern, as even with university graduates, the speed of speech, and level of vocabulary, can be too much for second language learners. Choose wisely.
Some of the TED videos (plus other videos) have been put on an educational site with added questions: http://ed.ted.com/ . Note that while these are not specifically for second language learners, they have the advantage of being specifically for ‘learners’, so they are often short and there are the added questions.
Here are a series of Russell Stannard’s training videos on how you can use ed.ted.com: http://www.teachertrainingvideos.com/edtech/index.html (His site is really something to admire, and it’s great how he has created that niche for himself).
Concerns about ed.ted? You have no idea what students (or at least your students) are doing on the site. It’s great that a video can be used in this way, and the questions and discussions made. But what then? Should we be using and sending students to this diverse range of sites, or just try to keep most of what we do under one system – i.e. the LMS?
Finally, here’s a new site also using TED videos, but specifically for ESL learners: http://tedxesl.com/ . This site is still very small with not many videos as yet, but gives some ideas about how videos can be used for language learning.