Why does Youtube keep saying i need to upgrade to a modern browser when i'm already using one?, 9.0 out of 10 based on 1 rating

I’m using Internet Explorer 8 at the moment, but Youtube keeps saying i’m using an outdated browser and need to upgrade to a modern one. Then it lists some options, including Internet Explorer 8, the very browser i’m using at this moment. So why do i keep getting this message?