Lies, is that the word you're looking for? I can't recommend swapping one deception for another. Once you move from the video to the subject of your own dressing, she'll realize that the appearance of that video was no "accident", and she'll be more resentful that you manipulated her. I'm not gonna stop preaching this: A relationship built on deception is a relationship that is doomed to fail, and the bigger the deception, the harder it's all gonna crash down on you when -- not if -- it crashes.
Hopefully kathly can find a better way to bring the subject up, that is gentle *and* honest. You could show her the video, ask what she thinks about it, and then go into "There's a reason I wanted you to see that..."
More likely you won't need to because some time before it ends I'm sure she'll ask "why on earth did you want me to watch this?" "Well, funny you should ask..."
ralph