Fun fact: the opening before the real song kicks in is from "I Don't Want to Set the World on Fire" by The Ink Spots. The reasoning for this is the trailer was originally shown at the end of a 24+ hour long livestream hosted by Bethesda showing employees and a little puppet of the Vault Boy doing various shenanigans before Todd Howard showed up and said it was time to announce what everyone was waiting for. The opening of the trailer shows lightbulbs illuminating and the opening playing - almost perfectly mimicking the opening of the Fallout 3 trailer. Very fitting since this year is FO3's 10th anniversary.