Last night I watched Dr. Strange with my son. There's a scene at the end of the film that spoke to me as a Buddhist. Dr. Strange, battling an evil entity that lives outside of time, traps himself and his nemesis in a time loop.
Knowing that Dr. Strange cannot possibly win in a battle, the evil being says,"You can never win."
Dr. Strange replies, "No, but I can lose again and again and again--forever." The scene continues as the monster kills Dr. Strange but, due to the time loop, Dr. Strange reappears only to die again and again. In this way, at the price of his own life, he has saved humanity against the destruction of the evil being.
This is the Bodhisattva's Vow--trying to help all beings for eternity, no matter how futile or painful. Dr. Strange is willing to die an infinite amount of times to save the universe just as a Bodhisattva vows to be reborn for eternity to save all sentient beings. This vow may or may not refer to actual rebirth. In a more figurative way, the oath means to return to the present moment of the here-and-now and dedicate our lives to the well being of others. Even if that means losing forever.