This first happened three years ago and now I try to do it as often as I can. I was 15 years old, and my sister was 16. We lived in Buffalo New York, with both my parents and my sister. She has always been slim and average height, nice breast and very hot. She still makes me want to jack off whenever I see her.
One day I had this crazy idea! My sister has this small video camera that you can fold up and close while it was still recording. It had about 2 hours of taping on it so it was perfect. When you closed the camera you could not tell that it was recording. Whenever my sister went to take a shower, I snuck into her room and started her camera. I was exited and could not wait to see what I recorded. I positioned the camera so I could see her bed and her dresser area.
So eventually she got out of the shower and went into her room. I waited about two hours for her to leave her room and go pee, because I could not get the camera while she was in there. So when she was in the bathroom, I hurried and got the camera from her room before she returned.
I sat down in my room and started watching it. I saw her nude for the first time ever. I was rock hard, looking at her beautiful breasts and gorgeous pussy. I pulled my hard cock out of my pants and started to stroke. All I expected to see was her get dressed and do something else, but then she laid on her bed and started masturbating. I was so happy, and my heart was beating hard. I started pumping my cock harder watching my sister masturbate. Eventually, she had her orgasm. It was quiet, but she was moving in all sorts of directions. Then following a few seconds later my cock shot about four or five ropes of cum. It felt good and thankfully I did not get the camera messy. I deleted the video, and the next time she left her room I put the camera back.
I started to do this every time I could. I usually got to see her naked. Most of the time she did not masturbate, and sometimes she changed in the bathroom or in a different spot in the room. It was great.