Ok, I just wrote, like I said to youtube help support, emails, twitter and all that jazz, MY GMAIL ACCOUNT IS NOT LINKED WITH YOUTUBE ANYMORE, so therefore even if I do the 2-factor steps, doesn't matter, and I did, first thing I did, like 5 times... my gmail account is fine...Sigh...
IF as you say the Gmail was linked to the YouTube account, then using your two-factor should let YouTube know you are the legit owner; if in fact the channel still exists, and the hacker hasn't initiated his own 2-factor on the new email.
The 404 is ominous as it looks as though your channel may have been deleted; but I must ask you; did you even try the 2-factor, or did you simply assume that due to the email, it would not work? If you go to a lawyer and say you want to sue YouTube over a lost channel, be prepared to either be asked for a million dollar plus retainer just to start the ball rolling, or to be laughed out of his office for wasting his time.
Also if the channel has been deleted, even hiring a hacker will be useless. Uset-deleted channels are irrecoverable.
Except that a quick search does show another one 'user/alessio11' which has been around for over 13 years and has 221 uploads.Yeah, Insanity Films was just me before the hacking, I've noticed other 4/5 channels named Insanity Films appeared... I think the hacker is having lots of fun on my back trying to confuse the algorithm or whatever.