I recall seeing this sometime in the late 80s or early 90s. This was back when we rented VCRs from the local grocery store along with whatever was available on their very small movie shelf.
This was probably a compilation of short films but the only one I remember is this one.
It was black and white and involved a young child trying to find the answer to some question. He grabs a mask and goes into his grandmothers room and she is covered with a large medical shield over her bed. She’s hooked up to a breathing machine and you can hear it running. She looks out of it and he asks his question. He gets no reply so he leaves the room and discards the mask in a basket labled soiled.
In another scene he goes into his older sisters room (I believe) and she is being orally pleasured by her boyfriend under the sheets. Her arms are holding onto the bed frame as she writhes around. She may even be topless during the scene.
The boy doesn’t get the answer so leaves her room.
That is all I remember. Every so often those scenes spring to mind. I have tried searching for those scenarios but have had no luck. So since it has returned to my consciousness, I thought I’d ask here.