Yes, this behaviour also happens in our translation team.
It happens when two or more team members work in the same chapter at the same time.
I have not yet noticed it when the team members work on different chapters.
The reason for the jumps, in the above scenario, is that the USFM editor checks for updated saved chapter data on the website. When it notices an update on the website, it will reload the text from that chapter, so it has the newest and updated chapter.
Is this the case in your situation, or would it be something different?
Another reason could be a slower internet connection, so that there's a lag in communication, since the USFM editor communicates with the server regularly, and the focused passage is communicated and polled for every second.
Regards, Teus.