There is no need to copy/paste the URL if it is a link already. Just right-click and pick "Open in a New Window" will get around the stupid restriction. Then tell whomever posted the link to edit it so it will work with a simple left click. All they need do is change the Target from "Current Window" to "New Window" in the popup and it will open fine.
This won't work: http://www.youtube.com/watch?v=GH3njEStKFM&feature=topvideos
But this one will: http://www.youtube.com/watch?v=GH3njEStKFM&feature=topvideos
The second one's target is "New Window". Right-click the first one and open in a new window and you'll find that works too.
Over a year ago I added the
button to the editor to embed videos directly but I can't force anyone to use it: