It does seem like that link is broken - I was able to navigate to the file by going to Fix Central.
I did the following:
Go to IBM Fix Central site
http://www-933.ibm.com/support/fixcentral/
Product Group = Lotus
Product = Lotus Document Manager
Installed version = 7.0.0
Operating system...
click continue
Check Browse for Fixes and check do not show fixes that change my installed version
Click continue
Check the box for Recommended group: 7.0-DomDocMgr-i5)S-Recommended-Group
Click continue
Pick how you want to download
click continue
pick DDM_Desktop_Enabler-200911119.zip doubleclick to start download