I secretly watched the video of my sister getting fucked by her boyfriend

I knew my sister had a boyfriend. Two or three times she even brought him home. Our house is made of bamboo. One day it was through small holes that one could peek inside the room. One day sister brought her boyfriend home. I was in another room. I don't know why but I peeked inside through the hole so what would I see! my sister was made of a mare and boyfriend was fucking her from behind. Didi's fair ass appeared to me.