The music was integral to the plot of the movie (rather than just something playing on a radio, etc.) so they were smart enough to buy the rights in perpetuity. Like I said, there's no way that they would have been able to pay for the rights for 15 or 20 Beatles songs for the DVD release if they...
Music probably isn't an issue for I Wanna Hold Your Hand because Universal must have paid for the music rights in perpetuity when the movie was made or it wouldn't have been released on DVD or even VHS.