Collections contain several videos that are meant to be viewed together. This is how you would go about creating a playlist in Uscreen.
Before creating a collection, upload all the videos you want to add to the collection under the video section. Make sure you've set thumbnails and all the regular details you would normally set for a video too.
NOTE: If you don't want the videos in a collection to appear in the catalog along with your other videos, don't publish them. You'll still be able to add them to collections without them being published. That way you don't have to worry about videos being watched out of context.
Navigate to Content > Collections and click Add New. Fill out the collections details and Save your changes.
Next head to the Playlist tab and add the videos you want to be part of the collection.
Lastly, head to the Appearance tab and give your collection a category.
If you're ready for it to appear on your catalog, you can head to Publication and publish it.