Hold up now. I did not say that YouTube was going to block Internet Explorer users. They are going to block users of Internet Explorer 6 (and presumably prior versions). Internet Explorer 6 is the version of IE that came with Windows XP, and it's the last "Classic" version of IE before Microsoft threw the GUI in the blender. IE 7 and IE 8 are both ugly as sin, but that's the least of my concerns with Internet Explorer. IE specifically does not block ads and cannot be made to do so - that's my biggest beef. But I'm using Firefox (actually Portable Firefox) and encourage others to do the same. Or if Mozilla creeps you out (their funky licensing or their rising popularity) and for some reason Google doesn't, they offer a browser called Chrome. There's also Opera, which scared people away by being the last paid web browser (it's since been made free). Fifthly, there's Safari, made by Apple, recently released for Windows. So there are five major choices there. IE 7+, Firefox, Chrome, Opera, or Safari.
The real story here is that many people actually still have or still use IE 6. It actually isn't a bad browser, compared with IE 7 and IE 8. It just needs to be configured properly to be safe (or relatively so). It's not going to do the tricks Firefox can do, but it's not bad to just hit the Net real quick for something, in a pinch, or if that's what's installed at work. The fact that YouTube is not a safe site to be accessing at work is entirely beside the point. I don't know what your job is. Maybe you have a lot of down time and YouTube keeps you sane. I don't know. Don't really care, either.