spending 40 minutesAre you sure you are thinking about TED talks (or perhaps they've changed the format)? Because the selling point of TED talks (not TEDx Talks, which is something different) is that they are 10-12 minutes and to the point. And no matter what you might think of the subject most of them are great masterclasses of clear and precis presentation techniques. You can learn a lot about public speaking and presentation from them.
All that being said TED has gone massively downhill over past few years. When they first started TED really did manage to get some of the biggest names in their fields to give really unique talks. However as they've massively expanded the number of shows they do they've become less and less picky as to who they let on stage. This has led to their 'brand' declining and fewer and fewer prestigious people want to be associated with TED.
any decent book written by an actual scientist will serve you much better.
The whole point of TED talks was never to replace that book. Rather to get you excited enough to pick up that book, especially in a subject you initially had no interest in. In fact most scientists with books use TED as a platform to convince you to read that book.