How to efficiently copy a Windows library to a network location?

Background: I want to keep my media files on a network attached storage device in sync with the corresponding library on Windows. Consider video. Periodically, as the content of my Videos library changes on Windows, I need to propagate those changes (new files, deletions, name changes, etc.) to the NAS. Changes are to be propagated only in one direction: from Windows to NAS, never the other way around.

Copying (ctrl-C) the Video library and pasting (ctrl-V) to the network shared folder works just fine. It creates a directory hierarchy under the target shared folder that replicates (by name) the structure of the Windows library. But there are two problems: (1) it won't work the second time unless I first delete contents of the target shared folder (2) it does extra work because the vast majority of files are unchanged.

Microsoft SyncToy in "echo" mode copies only new or changed files, but it does not work with libraries.

Is there an alternative to SyncToy that will do an incremental copy, yet also work with libraries?

FYI my Videos library references multiple physical locations in my user profile. In other words, the video files are not all in the standard location C:\users\john\videos.