I guess this pretty much sums it up. Not much double waitlisters can do to improve their application. This is the transcript from the Live Chat from April 25th. Time to just wait and see if miracles happen...
ME: Hi, do you have any suggestions for applicants who were waitlisted in both Rd1 and Rd2? I have already submitted several update letters, the video, and two additional letters of recommendation. Is there anything else waitlisted applicants can do to show their commitment to attending Booth, if given the opportunity? Thank you for your response.
kurt: Unfortunately I don't have any additional recommendations. If you feel you have been thorough in presenting your case to the committee than it is simply a matter of waiting for the decision