Collections are useful for keeping your videos organized. You can add a Personal Collection under My Content, or a Team Collection under Team Content. By default, a video will not show in All Team Content unless it is added to a Team Collection.
Here are three options for publishing a video to a Collection:
Option 1: Under the video permissions
Option 2: Under "More Options"
Option 3: Drag and drop
If a relevant Collection hasn't been created yet, you'll have to create a new one before submitting your video. Learn more about Collections, here