It shows a way to see the progress of an ALTER TABLE statement in MySQL. Normally I'd say "that's a cool gadget for a special X-mas post in a blog", but he's dead serious about it: ALTER TABLE in MySQL rebuilds the entire table, which not only takes a long time on large tables, it also locks the table while doing it. In large production systems you cannot alter a large table without seriously disturbing the functionality of the system. Hence, you want to be able to tell the users how long the system is going to be down; progressbar.
Kudo's for finding out how to do it, but seriously, shouldn't you switch to a database that does not suffer from this ridiculous issue in the first place?