The power of Neodymium magnets, one of the powerful magnets on this earth which are used in Industries and even in the high range of Headphones for boosting performance and clarity. You can watch it the below video. When its passed throw a hollow copper pipe the neodymium magnets passing though it will look like floating in the pipe.
The demonstration with the dollar bill I saw on you tube done by robgallagher. The magnet is attracted to the dollar bill because of iron particles in the ink.