OOOH your iPhone videos look SOO NICE. And it's true, the stock cam on the iPhone 4 does a decent job for quick videos but if you wanted to stop being an amateur and use some real tools for video recording, Filmic Pro is what you need.
There are other Super 8 apps on the App Store but Levi's iSupr8 Film app probably does the best at capture the finicky flickery flippity of those Super 8 cams of yore. Best of all, it's free with new features.
There are already a ton o' vintage camera apps for your iPhone but this Super 8 app (which ties in to the J.J. Abrams movie of the same name) is as full featured and fun and free as they come.