Why does space look always black when we see videos from the ISS instead of seeing all the billions of other stars..?
One of the major reasons is exposure settings. When taking pictures from the ISS most of the time there is something else in the frame which is brightly lit; remember that there is less between the ISS and the Sun than there is between you standing in an open field at high noon. Can you see stars then? Of course not, they would be too faint for the ambient lighting.
So if a camera was set to show stars whatever else in the photo would be a blindingly bright smudge overtaking the entire frame.
Cameras are not particularly good at capturing images of multiple intensity light sources. If let the camera take in enough light to see the dimmer objects the brighter ones will wash out the rest of the photo. if you set the exposure low enough to see the brighter objects, the dimmer ones wont show up. Normally photos taken from space want to see the brighter objects, usually the earth or the moon. In situations where you want to see stars you have to design the camera with specially designed light filters and make sure you dont get bright objects like the earth or moon in the shot.
Camera exposure settings.
Simple explanation is that the stars are extremely dim compared to surfaces illuminated by sunlight (e.g. the ISS, an astronaut, or the moon surface).
If you want to photograph brightly lit things in space, you need a fast exposure so that the bright things don’t appear washed out white. With a fast exposure, the stars are much too dim to show up.
Most of the time you need to actually be focusing on stars to take pictures of them. Go out on a clear night and take a picture of something with your phone, like a tree. It’s unlikely any stars will appear in your photo, because your camera is focused on the tree. Videos taken from the ISS are either focused on the Earth or on something inside the station.