Hi
I don'tknow what 2.2 has but if it is the same or similar to version 2.41 which I think it may be, and you don't want to use the main sequence line for precise editing then clicking the play button in the clip preview screen will show the red play bar moving to the right. If you are zoomed right out (Ctrl + neg) then at any point you can stop the clip playing, grab the red cursor line and drag it to any point in the clip you want. You can then step along one frame at a time to get a precise frame and then simply click the red flag button (IN marker) or the blue flag button (OUT marker) . The green down arrow will then place the portion you have selected on the sequence line.
I would suggest however that as the clip sequence screen is quite small and as you have only 1 sequence line ( in this version), it would be far easier to simply place your 15 minute clip on the main sequence track and then use the sequence line cursor to select where to make the cuts in your clip checking the precise position of these in the larger right hand screen and using the < and > controls for precision positioning. You can then simply remove the part of the clip you isolate between the cuts.
This is simpler and more precise. You can also see the soundtrack if precise audio cuts are required, something which is not possible if you just use the clip preview screen. Furthermore you can zoom the main track with a slider or the mouse scroll wheel.
Version 3.xx is little different to this as far as these actions go but (IMHO) it runs a lot slower and has multiple video tracks acting as overlays to the main sequence but there are more features. You would need to try version 3.24 or 3.28 which are the latest. If you still have the setup.exe file for your current version then you can download either of these and give them a try. If you don't like them then you can simply re-run your version 2.2 exe file to revert back.
Nat