When you register as a Bet Angel customer we have to permission your account to be used with your chosen exchange. For that to happen we have to submit your username to the exchange. If we don't do this you will be unable to use Bet Angel. We also need some way of tracking your usage so we license the software by your username, not by installation. This means you can install multiple copies of the software on multiple computers without requiring additional licenses.
You should be re-assured that we have processed many hundreds of thousands of user logons to Betfair without a single problem. If you have any questions or concerns about us please feel free to contact Betfair directly. The team that looks after the software vendors can be reached by emailing firstname.lastname@example.org