Hub allows you to download a section of your export using filters. Here's how you can do it:
In your project, go to the Tasks tab.
From the filters present above the task list, filter the task list until you are left with the tasks you wish to export.
For example, if you wished to only export tasks completed in less than 5 minutes, you would click on Filter, then on Duration, and pick Less than 300 seconds:
To download the tasks in the list as an export, click on the Export button to the right above the task list.