To start off, Niels Leenheer gives a talk about the importance of when to use and also when not to use progressive enhancement. You can imagine that a video tag can be replaced by an image for devices that don’t support the native video tag. But Youtube without videos, yeah, that won’t work at all. After the audience loudly applaudes to an image of ‘goodbye Internet Explorer’, he emphasises that browser wars are a good thing. When every browser would run on Webkit (or nowadays even Chromium), the need to make browsers better would decrease. Also he said:
IE6 was a good browser
Daring statement! But then when you think about it, at the time it could do awesome things. IE6 became a pain in the ass for developers only later, when modern browsers came around and people were still using IE6. Key takeaway of the talk: think about users, not about browsers.