Even proper TED talks can have some big issues. I'm thinking specifically about Kary Mullis getting up on stage and saying anthropogenic climate change isn't real because he found a study that says there's a current that fluctuates and absorbs anything we do--or something to that effect. If you didn't know anything about Kary Mullis and just heard "Nobel prize winner" you might assume he's credible. In actuality he was a pariah for talking out his ass about things he doesn't have expertise in and doesn't understand, specifically his climate and HIV/AIDS denialism.

It's always a good idea to approach any lecture with a critical view, but I can see why TED talks might warrant extra scrutiny. They project expertise and authority which may or may not actually be credible. The organization has a mottled record of vetting their speakers for actual expertise. (ETA: actual expertise in the content of their talk. Obviously Kary Mullis had actual expertise, just not in the things he said on stage)