Note that this finds threads and not posts within them.
And then you can take the following actions on matching threads:
I don't believe we showed this with bulk user management, but the same option applies there. If you're unsure if the matches are correct or if you want to manually filter them down, you can click the "view or filter matches" link. For bulk thread management, you'll get results like this:
You can use the check boxes on the left to manually filter which of the matched threads will be updated. Clicking the "batch update selected" button will return you to the action selection page. Choose the action(s) you want and let the changes happen.