What is Activity in the Blog Activity Plugin?

In the blog activity plugin, just how is “activity” defined?

If I’ve got these statistics:

Updated blogs in the last:

Five Minutes: 1

Hour: 3

Day: 18

Week: 49

Month*: 78

Posts in the last:

Five Minutes: 0

Hour: 0

Day: 27

Week: 179

Month*: 636

Comments in the last:

Five Minutes: 0

Hour: 3

Day: 25

Week: 173

Month*: 381

What happened in that one “updated” blog in the last five minutes? It wasn’t a post, it wasn’t a comment…so what was it? What’s the definition of “activity”?

(Also–as a request–this plugin would be hugely useful if I could pick a specific month, instead of just the last month. Is there another plugin that does that? Or an easy way to edit this one?)

Thanks for a great plugin, generally speaking!