Some videos at youtube require you to verify your age to make sure you are old enough to view the videos. It's easy enough to enter this information but it's still a pain to have to do this. If you aren't logged into youtube you need to do this for every age-restricted video you view.

There's an easy way around this if you are using Firefox. I'm not sure exactly how it works. But when you have it installed it allows you to view any age-restricted video on youtube without having to go through the verification step or login to youtube.