Here’s a bunch of resource where you can find cool seminars by some hardcore scientists (I mean not the kind of pseudo-scientific, inspirational talks that you’ll find over the web).
In English
Feynman’s talk are an endless source of excitment. Project Tuva are a must-see, but many other videos are available on Youtube (Fun to Imagine, the pleasure of finding things out)
The Chua’s Lecture – Very recent lectures on memristors and chaos– fascinating !The Royal Institution – very cool videos about scienceEdge – There’s a lot of cool videos on a wide variety of subjectsIn French – En Français
Les Ernest – L’ENS offre un grand nombre video (15 min) sur toute sorte de sujets, par les plus grands experts du domaine.
Seminaire General du departement de Physique de l’Ecole Polytechnique – traitement nettement plus poussé (1h) sur un sujet particulier de la physique.Enjoy !