>>510308455
You are confusing url with post data. In a youtube (or twatter) link anything after the ? is data to be processes not part of the base URL. Youtube usernames are not case sensitive because the url isnt case sensitive but the data strings (?v=skljfSDFsdkfj) can be case sensitive

On twatter the user handle is part of the base url. You can use either case because its not case sensitive. Twatter will remember which case when you signed up and show it in that case but it makes no difference to the url.. Regardless of your butthurt GB = gb = Gb = gB in a twitter username