I recently was over my sister's (who is 22) apartment for a visit. She had gone out shopping for a while, so I decided to watch some TV. I had noticed a videotape in the VCR, and I was curious what was on it. I hit "play" and to my surprise it was a video of my sister having sex with her boyfriend! And it wasn't just like they put the camera on a table and hit 'record' either. It was almost like a porn type deal, someone actually was filming them, getting different angles and alot of closeups. As I watched it, it started to arouse me, I knew it was kind of wrong but it turned me on so much I masturbated to it. My sister is a very attractive girl, in great shape your typical "hot blond" I must admit, nice fit body long tan legs, nice size breasts, but to see her naked having sex with closeups of everything was new ground for me. Should I tell her I saw the video? And was it wrong to masturbate to it? It turned me on so much I had thoughts of making a copy for my own "personal" use, would that be wrong? What should I do?