Moving downloaded swings to your iOS photo roll
Create "content" for use in split screen view requires that the video be saved to your iOS photo roll. This option will be expanded in the coming weeks to use any files in your iCloud account. Until iCloud transfer functionality is released, the easiest way to import video to your photo-roll is to air-drop it to your iPad (or iPhone) from another iOS device. This works even if the file was not originally in the sender's photo roll because iOS automatically classifies incoming airdrops into videos and photos and moves them to your photo roll. If you are not familiar with AirDrop there is more information from Apple on how to turn on and use AirDrop For iOS: How to use AirDrop on your iPhone or iPad.