As you may know, TED is a collection of speeches that, “bring together the world’s most fascinating thinkers and doers, who are challenged to give the talk of their lives“ (in 18 min or less). There are some fantastic resources available on TED, but recently they began also adding non-TED speeches.
“On TED.com, we make the best talks and performances from TED and partners available to the world, for free. More than 450 TEDTalks are now available, with more added each week. All of the talks feature closed captions in English, and many feature subtitles in various languages. These videos are released under a Creative Commons license, so they can be freely shared and reposted.”
Take a look!: http://www.ted.com/talks/list