By showing both the task burndown and the story burndown we help the team see the two key aspects of their sprint work. Are they on track from a task POV - and are they completing stories early enough in the sprint.
The task burndown (1) runs of the left axis whilst the Story burndown (2) is shown on the right axis.
This shows a typical though unhealthy pattern in teams - namely, only completing stories on the last day - a form of 'mini-waterfall'.
SenseAdapt charts are intended as a starting point for action. Clicking on the bubbles on the line (1) gives the pop table, which users can sort or open up (2) the task or story in TFS