"moving quite quickly" is the earth turning under your feet, of course. Relative to each other, objects in the sky don't move particularly fast. In fact, there are only a few situations where you can observe that relative movement visually.
So that 5th "moon" (actually star 45 CAP, HIP 107302) will stay in the vicinity of Jupiter for a few days while Jupiter and its moons move past it. In fact, Jupiter moves in front of it about now for some viewing locations in the world (I think Mike may have posted an article on this)
So what relative movement can you detect visually over, say an hour or two of observing?
I can think of three options:-
1) The rotation of Jupiter. If your magnification is high enough and seeing is good enough, you should be able to detect Jupiter rotating. If the Great Red Spot is visible, that can be a marker to the rotation - over a few hours.
2) The movement of Jupiter's inner moons. Io and Europa whizz around Jupiter fairly quickly, so you can often see them move relative to Jupiter over 15-30 minutes. Often very clear as one approaches the disc of Jupiter - the gap narrows/widens quite quickly. Also the movement of one of their shadows across the surface of Jupiter can be clearly seen over 30-60 minutes.
3) The movement of the Moon. The Moon moves a fair distance against the background stars in a short period. Think of the recent eclipse as the Moon moved across the face of the Sun in only a bit more than two hours. The Moon moves some 360 degrees across the sky in 28 days - around about half a degree an hour. So if you are watching the Moon, you can see it pass in front of a star (or occasionally even a Planet or a special star - the Sun) and then the star re-appear. The movement is fast enough to pick it up with your telescope over minutes. Check Australia Sky & Telescope - it reports coming occultations of stars by the Moon.
Happy viewing!
