The problem with flow analysis is that it is doing a reverse lookup on the IP addresses and it is getting your ISP domain names. The only way around this from what I know is to deploy deep packet inspection which can look at the HTTP headers and extract the actual domain names. See below for a video which shows how a product called LANGuardian could be used to report on Internet usage through the SolarWinds interface. This is an example of how DPI can be used to report on proper domain usage.
Hope this helps,