How to trim a video based on a condition

edit

trimming the video isn't the issue, I want to automate the process using OpenCV. I want to find from which frame the drone starts to move

Well you got an interesting task here, i don't know the solution but maybe i can give some ideas. The good thing is that the video is from the 1st person view of the drone.

I found this link. https://www.pyimagesearch.com/2015/05...

If i understanding this correct

1. Get the first frame(no movent) and use it as an anchor.
2. Do some preprocessing on that image (gray scaling, blurring)
3. Get the next frame, do the same processing on this image
4. Compute a diff between first frame and current frame. If the diff is bigger than a certain delta , the background changed and the drone is most likely moving.
5. Repeat on every following screen until you detect a movement (diff >= delta)