Canon POWERSHOT D20 User Manual page 45

Editing Movies
Save the edited movie.
Press the _.v buttons to choose [L_, and then
press the @button.
Press the 4_ buttons to choose [New File],
and then press the @ button.
The movie is now saved as a new file.
To overwrite the original movie with the cut one, choose [Overwrite]
in step 4. In this case, the original movie will be erased.
[Overwrite] is only available when memory cards lack sufficient free
space.
Movies may not be saved if the battery runs out while saving is in
progress.
When editing movies, you should use a fully charged battery or an
AC adapter kit (sold separately, p. 165)_
d)
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