The continuous trace is pretty self explanatory in that it continuously pings the hops for new data.
The images on the right show how to start a continuous trace and the general view once the trace has started.
Any trace route can be switched to continous using the drop down menu on the tab toolbar.
There is also an option in the drop down menu that allows the trace ro run once every minute.
The traceroute table will update as an when new data is available providing a real time view of how a certain route is performing.