Your issue is, the Code is not able to find the file "_version".
I would suggest you go to coursera_dl github page -> https://github.com/dgorissen/coursera-dl
Download zip from the link which can be found on the right side of the page.
in the zip file you will be able to find a folder by the name of "courseradownloader".
Extracts all the files in this folder into yout C:\Python34\Scripts folder.
It will work like a charm.
PS: I would suggest you use .netrc file to store Username and password.