I'm just getting started following the tutorials. There's no "Add itemslot" button that appears after adding the hand to the item parent field like it shows in the video. There is however an "Items" game object already shown as the child but when I drag it in the dialog box says not valid. Thanks.
I believe you're trying to use a third person item parent as a first person one - the first person visible items must be parented by the "First Person Objects".