Taking liberties.

This week we worked with Mair's second dagger play. there are some points to be aware of in our dissection of this flow. One of the things I hate in instructors of HEMA is the "clearly they wrote something wrong in the treatise" mind set. I always feel that where possible, the assumption should be that our understanding of the technique is most likely flawed.
With this mindset in mind, I (in full expectation of contradiction) suggest there are two mistakes in the play, one in the illustration,one in the text. The text states: Please note this is based upon the translation work of Kendra Brown, Rebecca Garber, Mark Millman, Jon Reynolds and Amy West hosted at http://wiktenauer.com/, so thank you to them. The text. Item: conduct yourself thus in this device with the onset.
 

Wind yourself with stabs and with thrusts doubly in at him [so] that your left leg comes in forward and [you] stab him at his right side [so] that the thumb stands by your rondel. If he thus stabs at your right side and you stand with your right foot forward, so take that away from the binding behind his rondel [so] that your thumb is [shall be] above on your pommel. Immediately step with your left foot behind his right(1) and set your left hand behind his right elbow; shove him therewith from you and stab him at his neck. If he has thus set on, so set your left foot back and grab with your left hand(2) outward over his right and stab him at his face. If he takes that away with his dagger, so grab(3)with your left hand on his right; push him therewith under himself and thrust him in his face. If he thus thrusts doubly at you, so grab with your left hand on his right arm, step with your right foot behind his right and shove him with strength from yourself. 

It is this section (1) that I feel gives the first clue that something is amiss if his left foot is forward and the dagger is in his left hand. Play as illustrated has the right elbow far behind the torso and the right leg rearward, this makes it impractical to step behind with your left unless you circle, leaving his dagger (by assumption still in the left hand)free. If however the left leg is forward with the dagger in the right hand stepping behind his left leg with the weaponised right arm pinned makes utter sense. This I feel is backed up by the movement back of the left foot and the use of the left hand to displace(2) and grab(3)
Here is the video of our take on this. I have left the mistakes and imperfections in so that you can see us working through.