Okay, I didn't really fix Youtube myself, however I did alert Google about an issue plaguing a lot of Google Apps users, me included.
When I first started out with Google Apps some 3 or 4 years ago the service didn't support all of Google's services. It didn't take long before most of them were fully functional, and when Google+ finally became available for Apps users after a lengthy delay, all important Google services had finally become available for Apps users. Unless you were outside of the countries were Youtube had officially launched. And by officially launched I don't mean available. Unless you could select your country in the footer, Youtube wouldn't work on your Google Apps account.
I'm not sure who exactly who was affected by it, but at least my Norwegian account was useless with Youtube. I'm pretty sure it was the same situation in the other Scandinavian countries as well.
However, sometime last year Youtube finally launched officially in Scandinavia, so in theory it should have been working by then. Sadly, I was still presented with the same error message as before, telling me to activate Youtube in the Google Apps control panel.
Only problem was that Youtube weren't in the list of services that one could enable. Darn it. Oh well, I figured I would just wait a little longer, expecting that the issue would be resolved sooner rather than later. But when I tried again in the end of January this year, it still didn't work.
As I'm only using Google Apps for my family I haven't seen any need for Google Apps for Business, the pro version of Google Apps, costing $5 per user per month. That would have been $240 per year for our four accounts, which it's not really worth when it's just in use for personal purposes. But now I decided to upgrade, even only for a month, just to access Google's premium support to try to resolve this issue once and for all.
After a short-ish phone call, I continued communicating with the Google Support team via email. The case was passed on to a few different tiers of support, and after a couple of days I got an email saying they were working on the issue. Since then I've received 1-2 emails per week telling me that they still were working on it.
Until today, when my most recent point of contact at the Google Enterprise support team emailed me, saying "the issue has been successfully solved". Nice! It took three weeks from I first contacted them, but that's nothing compare with the three years or so I've been waiting to finally being able to log into Youtube with my main Google account.
Finally these switched appeared in my Google Apps control panel:
Sweet!
Now I just need a migration tool to transfer/merge my old account with my Google Apps account. Oh well, I wouldn't hold my breath.