This video based on the legend that at the first Ecumenical Council, at Nicaea in 325 AD, St Nicholas was so angry at Arius’ heresy about Jesus not being fully divine and human at the same time, that he punched him right in the face.
For this he is thrown into chains in a cell, and the Fathers threaten to depose him as a bishop.
Later, Our Lady and Our Lord both appear to him in his cell, and restore to him the Gospel Book and his episcopal pallium, thus restoring him as  Bishop of Myra.
This Council gave us the main part of the Nicene Creed, which is included in the film.