If you have Windows Vista or more recent, you can use the inbuilt resource monitor (admin privs required).
- Start the game
- Start searching for games
- Open the resource monitor (
Win, resource monitor,
- You should find the game at the top of the
Network tab. Click on the checkmark.
- Now, network activity from the game appears in orange on all graphs.
- Join the game; start playing.
- As soon as you have a spare moment (maybe you're in warmup), alt-tab to the resource monitor.
- Look at the graphs and at the B/sec readings. They have your answer.
It's clunky, but it should work for all games and apps alike. The only "problem" is applications won't show up on the list until they do some networking.
If you have more than one process you want to measure (say, the game and mumble), just check them both.