How would you model a use case that describes providing additional information to the user giving him/her a better understanding of the system state but doesn't require user interaction?
For example, playing back a log, and the system provides visual indication on the timeline of specific log events? My reckoning, in the aforementioned example is that the user may elect to fast-forward/rewind the playback to that moment, but is not required to execute such an action.
The use case would likely be Provide System Status Information. How this information is presented can be described in the scenarios of the UC. So, as you describe it, there would be an optional path that allows to FFWD to some further information stream.
Just remember that use cases are about added value. Not about functions. You can describe various scenarios inside a UC which can be of arbitrary complexity - as long as they are build around that single added value of the UC.
