I don't think anyone is going to be banned for using this. The Game Manual talks about data mining and here's what it says:
The use of web-based data mining tools, “crawler bots,” or any other software designed to use our bandwidth intensively is strictly forbidden, and your account will be banned. If you really want access to large amounts of data, ask one of the BBs, and we’ll do what we can to provide it to you.
So keeping in mind the bold part, here are some approximate numbers:
- The amount of data downloaded by the browser user to open BB welcome webpage: 1.9 MB
- The amount of data used to get boxscore from BBAPI: 25 KB
- The amount of data this tool uses to gather statistics about single game: 12 KB
This tool or any BBAPI calls are less than 1% of normal webpage content. And this tool uses data that is encoded, and thus is likely to use less data than the BBAPI.