Hey,
when using DropboxOAuth2FlowNoRedirect().finish() it doesn't return the user_id of the user authorizing it.
Tested with the following code:
flow = dropbox.client.DropboxOAuth2FlowNoRedirect(dropbox_app_key, dropbox_app_secret)
authorize_url = flow.start()
print("Auth URL: " + authorize_url)
result = flow.finish(raw_input("Enter the code: ").strip())
print(result)
It returns the access code and an empty string.