Canon PowerShot V10 Advanced User's Manual page 110

Caution
Because editing is performed in approx. 1 sec. increments (at the position indicated
by [ ] at the bottom of the screen), the actual position where movies are trimmed
may differ from your specified position.
Movies shot with another camera cannot be edited with this camera.
You cannot edit a movie when the camera is connected to a computer.
Editing is not possible while the camera is connected to a smartphone via Wi-Fi.
For extensive movie editing, consider using an optional household power outlet
accessory.
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