Import from Photos vs. import from SD

You are partly right. Importing directly into iMovie from the SD card will place the clips into the iMovie library without the necessity of keeping the files on your Mac desktop. The duplicate original will remain on your SD card or camera unless you erase it.

One way of using videos from the Photos app is, as you say, to export them to your desktop and from there import them into iMovie. This would result in duplicate copies both on your desktop and in iMovie. However, you need not retain the files that are in your Mac folder. If you delete the files from your Mac folder that will not result in their being removed from iMovie, because iMovie has stored a duplicate copy of the clip in the iMovie library. Keeping both sets of videos would result in using twice the space on your computer, plus you would have an additional copy in the Photos app. On the other hand, storing the Mac folder on your Mac or on an external drive would would allow easier access to your files for future use.

The recommended way of importing clips from the Photos app into iMovie is to access the clips from the Photos media sidebar item of an iMovie project. Clicking on "Photos" in the iMovie sidebar will display the Photos app photos and video clips in the media browser to the left of the preview screen. You can display them by Years, All Years, Albums, Collections, etc. From the media browser you can drag them into your projects.

-- Rich

Yes, videos and photos imported via the Photos item in iMovie are imported as full originals into the iMovie library, where they are stored in the Original Media folder in the Finder. If you select an imported photo or video clip, and do a Find/Reveal in Finder, the Original Media Folder will pop up showing the selected clip highlighted.

However, you might not want to do delete imported media from the Photos app. The Photos app is a good place to store, organize, and manage your photos and videos. You can put them in albums, add keywords, create smart albums for searching for specific clips, add keywords and descriptions, and so on. iMovie is a great video editor app and has some good organizational features, but its storage, organization and file management capabilities are not as strong as the Photos app. Also, it is a bit awkward to retrieve your media out of the iMovie app if you want to work with it independently or use it in another app. You would need to search for it and drag it out of the iMovie media browser.

I keep my media in the Photos app, but also in Finder folders stored on two external drives. (External storage is pretty inexpensive.) I organize them with subfolders. Keeping them in an application like iMovie or Photos is O.K, but applications can get corrupted, mutate with subsequent iterations, or become obsolete.

-- Rich