Oblivion Knight - I updated the queries and that problem should be resolved. New version is 1.0.1. The file that changed is admincp/activitydetails.php.
weaver - my pleasure

Yep that's what I meant under future considerations by "Add forum grouping system for custom pattern queries". In other words, let the admin create custom groupings of forums (not necessarily related to the parent-child forum hierarchy) for activity tracking purposes. So that's definitely something I would like to add in.
I honestly hadn't thought about user exclusions or groupings, but that is certainly an idea for consideration as well.