Just interested really, I searched re-synch in the VSD help document, and it only came up once with a reference to a version of the software, what is it and why would you use it?

It could be useful if you have made several changes to your site, maybe deleted some files and added some other ones. Also if you have been unlucky with an upload and some of the apparently uploaded files don't appear on the site.

Or, if you have edited your site from a different location, using a different machine which also has VSD intalled, you can resync between server and local machine.