You can use mark in & out function to select the video flip in Filmage Editor.
1. Open a video project;
2. Right-click the video on the track;
3. Click Mark In & Out;
4. Look at the preview interface;
5. Click Mark In to choose the beginning of the flip and Mark Out to choose the ending.
If you need to repeal the mark, just click Mark In or Mark Out again.
The flip between the two marks will be maintained in the track. You can also mark the video through Mark in and Mark out in the menu bar of Tool.
Or just press I to mark in and O to mark out. Remember right-click the video on the track and click Mark In & Out first.