We need to know the initial velocity of a projectile leaving the Nerd-A-Pult.  That means we need the initial speed and the initial angle.  This video shows exactly how I measured both.

Content Times:
0:30 Taking measurements to determine the launch angle
1:20 Finding a triangle
2:02 Defining the angles
3:35 Determining the launch angle
4:38 Using the frame rate to find the change in time
5:08 Measuring the distance travelled during the first frame
6:12 Why initial speed and not initial velocity?
6:39 Determining the average launch speed