For muvee Reveal:

Simply click on 'Personalize' and select the 'Use all photos and videos' option under the 'Duration' tab. This option will preserve your original footage without auto-editing it.

For muvee autoProducer 6:

Click on 'Personalize' and select the option 'Best fit for videos and pictures' under the 'Duration' tab. This option will preserve your original footage without auto-editing it.

For muvee autoProducer 5 and below:

You will need to download the Keep It All stylePack to achieve this. As its name implies, this stylePack contains 12 styles that let you add simple effects, such as a sepia tone, to your videos/pictures without cutting out any of your footages. You can purchase the Keep It All stylePack here.