I have just found this recent 2012 TED talk by James Hansen. It has been on-line since 7 March. The number of views on TED is 120,748 today. The number of views on Youtube was 13,473. I bet that rises.
The talk is very polished. Hansen reads from a script and has obviously run through the talk several times. Hansen discusses the natural greenhouse effect, the Earth's energy imbalance caused primarily by fossil fuel combustion, sea-level rise, species extinctions, impacts on agriculture and the need to act for the benefit of future generations as represented by his grandchildren.