That the sister is interested in her foster brother's opinion is commendable. And assessing her worthiness from a man's point of view he can. But asking him to jerk off in front of her is kind of weird. He's going to get her, isn't he? Only this slutty girl is not scared at all - that's exactly what she wants. He ended up flushing a whole puddle on her tummy! Drove it.
There's a strange feeling about this clip, it's a bit old-fashioned or something. Both of them have hairy foreheads, which is more than strange nowadays. We are all used to all the ladies with smooth pubes and everything is well visible. And the stripes all over the screen - like there was damage on the film of a very old movie.
I'd love to help you do it