What does it mean if a concrete sewer line has been cleaned out, a camera has been used to get a video of the line, and the video shows standing water is the pipe?

Standing water in a drain pipe can be from two things; 1. a partially plugged drain pipe further down stream. 2. A belly in the pipe from settling. The key question is how well does this drain work for you? Can go run a shower or drain a tub without a backup?