I know there's a good chance this will become clear in a later video, but why are we making the player scene a class? What are the advantages?
Any GDScript file is a class. Class_name just gives it a name we can access globally in the project.
Here are several reasons to do that:
onready var player: Player = get_node("Level/Player")
And you'll get full auto-completion for it. The type checker will also ensure that the node "Level/Player" is of type Player.
For something like our player, that's mostly it. In other cases, it allows you to directly create a node of that type in the editor, if that GDScript class doesn't depends on its scene. That is to say, if it doesn't have other nodes as a dependency that are saved in a tscn file.