YOUTUBE HELP!

So I want to convince my parents to let me upload videos that show my face onto YouTube. When I first got one, she said no videos, but I eventually ended up posting anyway! But see I want to do like hair tutorials and such, so the whole idea of making movies the entire time, isn't necessarily great for that! They aren't that strict, and they let me have FaceBook, Twitter, Instagram, and Tumblr, so I don't see why I shouldn't be allowed to upload videos that Show my face! Please give me good reasons! I'm really mature, and I'm trying to write a persuasive letter. And I don't want to disobey! So, obviously I'm going to try and persuade them so I'm not going behind their backs!