That is indeed a bug. I’ve had another user report a very similar issue. I believe that the issue is related to the redirect URI which actually gets dynamically generated based on the page you are authenticating from.
I’m not sure how familiar you are with code, but if you open up class.youtube-for-wordpress.php, scroll down to line 1297 you’ll see where and how the URL is being generated.
Ah that’s a pitty. Our developer do not want to install a plugin which has a bug. It is running on more then 60 blogs then with tens of plugins. It must be manageble for them.
Do you have timeframe when this bug is solved? If not or it lasts to long I am afraid we have a show stopper and must search for another plugin