As I understand it, you can have dropbox sync with a folder of your choosing on your machine. Then you can give the Run As user for the Tableau Server machine, permission to access that folder and file. If they're pointing to the same place and both dropbox and Tableau Server have access, you should be able to sync. Am I missing anything Russell Christopher?
Does this work with Tableau Online or just Server?
I believe he meant that he installed Dropbox on both his laptop and on the Tableau Server host, with both instances of Dropbox pointed to the same filepath (c:\dropbox for example). Since the paths match, the workbook taking the extract, which points to c:\dropbox\myfile.csv on the laptop, can be refreshed on Server, since when it looks for c:\dropbox\myfile.csv, it's able to find the file it's looking for locally due to Dropbox doing its thing.