The first 30 seconds of the video reminds us of the best practice for adding and importing from multiple channels simultaneously. The video then proceeds to show you an overview of the inventory manager.

QUICK START TIP: You can import inventory quantities from any channel when you import listings at any time. You're also able to enter inventory quantities manually or download an inventory stock list csv file from the inventory manager, adjust it then import it again to adjust your inventory levels in bulk from a csv file.