nobody is asking you to defend yourself, nor does anyone want your username (at least not to my knowledge anyway) - not sure where you have got that impression from?
If your claiming that someone has hacked your youtube account and changed the username (I assume?) and posted that comment to another foccers account, then thats an issue you will need to raise with youtube/google.
I suggest if you have not done so you do this as a matter of urgency, because if someone has your login for youtube, they will also have access to your google+, your gmail/googlemail, and possibly one or two other services which can be/are synced with youtube.
As for "what is happening here", in relation to this site, nothing whatsoever is happening.
As per the post of mine you have quoted, I have taken all comments about this issue from any threads around the site and dumped them all in one place, so that this single thread is where all the off topic stuff relating to it is contained, rather than muddy posts around the whole site with it - seems to make sense to me?