Here is a video about standing vs sitting.
Although it is about guitar, it translates pretty good to bass too:
After watching this video, I realized one of my main problems with sitting vs standing: That I tend to tilt my bass abit while sitting, so I can see the fretboard, which doesn’t really work when standing. So even if you have your bass strapped that way that you have it exactly in the same position when you are standing and when you are sitting, this is a thing that might throw you off.
I try to not tilt my bass so much now when sitting, because for me, that is the main difference when sitting vs standing (I tend to have my bass a bit lower when standing, because it feels more comfortable).
I just searched youtube if there is such a video specifically for bass, didn’t find one, but found something else. How to stand on a double bass:
