You have an existing YouTube Channel for your business with a number of videos (in my case, it was called “SmartluxBalances“).
You also have a Google+ page for this business or activity (“+BalancesLu“). The channel and G+ page are not connected, so when someone clicks on the “Videos” tab on your G+ page, no videos show up:
Instead of uploading your videos again, you want the existing videos from your YouTube channel to appear there.
You’re using your personal G+ profile as the current manager (and owner) of your G+ page.
Your YouTube channel is not currently connected to a G+ profile (otherwise you’ll first have to disconnect it).
1. Go to your G+ page’s settings and add a new manager. Indicate the exact email you’re using to log in to your YouTube channel. Sign out.
2. You’ll receive an email to become a manager of the G+ page. Click on the link (or better, copy it to an incognito window). This is where things become confusing because you’ll have to set up another personal G+ profile. Just do it (you’ll delete it again in the next step). I recommend using your company’s logo as profile picture. Your former YouTube account is now a manager of your G+ page, too.
3. Still using your former YouTube account, go to your G+ settings and delete the useless profile that you’ve just set up in step 2. You’ll still be a manager even after the profile is gone.
4. Go to your YouTube account settings and click on the option to connect your channel to a G+ page. As a (new) manager of your business’s G+ page, you should now be able to select your G+ page as the new name for your YouTube channel:
If things didn’t work, head over to YouTube Google+ Integration for help.