Our organisation has felt pain with this for several years, specifically in the Test Plan screen. It is tedious enough for 5-10 Test Cases, never mind the 100+ you mention, jpatel8.
And I think the video, JohnStreeter, shows the moving of Test Cases from one TF into a new one, rather than creating new copies in the intended destination.
But still, even if you have no choice but to make copies, creating a hundred copies in the source folder and then using John's mechanism to move them to their new TF all in one go would be very labour-saving!
The Quality Management screen, despite its imperfections, was a great step forward for doing anything of this sort of nature.
Oh, and I'm editing this to give an honourable mention to Test Sets, as the functionality -- designed for use in Regression scenarios -- to use when you don't necessarily need proliferated separate copies of the TCs, but do want to be able to manage them in a separate context.
--Nev.