Obviously

It's my only chance really. Even if I were to confess and have my GF demand for the video, M could very easily just edit it to be a whole lot more damning. Likewise, if I play along and be a good boy for her, she could also edit my face out of it and then send then evidence. So, the best course of action would be for me to play along as best as I can, be the perfect little servant for my Mistress for the week and do my damned best to not get caught in the act.