Half the fun of browsing the internet is watching videos. So imagine the disappointment of many people to discover that you can't even do that. That would make people normally go on their computer to do stuff like that, but that kind of defeats the whole object of having it on Xbox then doesn't it?
I know videos on websites that don't use flash player will play just fine on Xbox, but 90% of the videos I have tried to play don't work because of the lack of it. It makes even less sense that you can't watch Youtube videos on Xbox, despite there being a Youtube app for Xbox!
I seriously recommend you make support for flash player, among other plug-ins. It would make the experience of browsing the internet on a console so much more enjoyable. I am honestly dumbfounded as to why you didn't add it in the first place.
Please take all this into account, thankyou.