With technical analysis, it is very common that the video recording made will be longer than the part intended for analysis. This may be accidental; you started recording too early and finished too late; or there is only a short section of useful footage within the recording you made. Or, it might be deliberate; you want to analyze a section of a much longer video. Whatever the reason, trimming is often the first step towards analyzing a video file.
Note: Dartfish 9 no longer has the cue in/out markers shown in this tutorial. However the principle shown of finding the in point and setting the in point remains the same.