iMovie for Mac: browser
The area in iMovie that displays the media in the item selected in the Libraries list or content library. You select clips or portions of clips in the browser to work with them.
You can filter items in the browser to show all clips, show only favorite or rejected clips, or hide rejected clips. You can also search for clip names in the browser, set the size and zoom level of the items, and choose whether to show audio waveforms.
Ranges in video clips that have been rated as favorite appear with a green line at the top. Ranges marked as rejected appear with a red line at the top. Ranges that have been added to a project are marked along the bottom with an orange line, and video clips with keywords added in Photos or previous versions of iMovie are marked with a purple line.