Autoplay on tumblr?! Help !!!!?

This is my tumblr page, please click, itll help you out kinda

http://brooke--hiltt.tumblr.com/

Kay, I know everyone hates autoplay on tumblr but I thought, whatever, they can pause it if they want. BUT NOW I NEED HELP, when you start scrolling down, the music bar doesnt stay there like it is supposed to !! It stays at the top of the page and im really confused.

I thought this could help too even though its just a random tumblr person who I picked,

click it !!

http://niggawitdreadz.tumblr.com/

SEE ?! He also has an autoplay bar, and his takes up the whole bottom of his screen and when you scroll down it stays there, I want to get that really badly but dont know how ):

Please help me?! ]=