has youtube gone through some changes or something?
 

i notice most people's accounts with random url's? and i also received two mails of youtube, that you can create your own username but if you do nothing they generate a random url based on your account name with a @ sign

Yeah for some reason youtube has assigned everyone a handle for their usernames, and if you don't pick one then they just make one up for you. I think it's suppose to make other people find you/identify easily.

It's probably to stop people pretending to be big YouTube channels like Pewdiepie for example.