Expansion drive that once had the OS should fist be cleaned by deleting all partitions and then creating a new partition.
Open explorer, right click on My Videos under Libraries, - properties to see what folders are on the link. Remove the one you don't want. Then try to remove on the one on the expansion drive.
But that's the point: I couldn't delete folders (directories I call 'em) on the expansion drive.
But, hey, the problem has gone away. The computer has Chinese language on it as well as English. Even though I was writing in English in the 'rename' boxes I suddenly noticed the bar at the bottom of the screen where it said it was set for Chinese.
I set it for English and things went better.
I went to a cmd prompt and renamed the directory successfully but then saw windows explorer still listed two 'my videos' even though the cmd box listed no such thing.
don't know how I fixed it. just kept trying, moving one 'my videos' into a purposely created 'temp' dir to get it out of the way and stop the 'two same names' problem.
renaming. deleting. fixing that 'chinese language' thing.