Contacts are based on the 3 system questions First Name, Last Name and Email address. Those 3 questions are included in the Personal Information group and contacts are matches based on exact matches of all 3 of those fields.
So in your video, you used the same email but not the same First name or Last name for each of those registrations, that’s why you have multiple contacts.
As an example, it’s common to have a user register themselves and their partner in a group registration, use the same email for both registrations but obviously different names, those are (and should be) different contacts within EE.
May I ask what it is you are looking to do with the EE contacts?