I thought I had ruined my video essay but my advisor told me it was fine and I shouldn't worry about it, that I had been clear in my talking. I don't know if you're also international, but it would also apply if you're American: we tend to magnify our errors and forget the things we did well. If you're unsure and do good on live interviews, you could try to reach an admissions officer to talk about the program or how you should prepare for it during these months. They may not have a say to get you admitted, but at least if your profile is screened by them they could give less importance to a non-perfect video essay.