My Test Complete execution normally takes more than a Hour or so. Hence in the Indicator popup if we have the timer which will display the HH : MM : SS running. This will help us to know approx. ...
Yes, the extension works on TC version 12.
Where did you put the file for use? It should go in your TestComplete 12\bin\Extensions\ScriptExtensions folder. If you put it there, try opening File | Install Script Extensions and click the "reload" button to see if it comes up.