Have you considered that the bishop may have produced his video well in advance of Divine Mercy Sunday and that it only happened to be played for the parishes on that Sunday? IOW, while you were anticipating Sunday Mass to be focused on DMS, the archdiocese didn’t have that same focus since celebrating DMS is optional. Even my own parish, which is quite orthodox only mentioned DMS in the announcements as an invitation to attend special services later in the day.
I know how you feel, though. When St. Therese of Lisieux was named a Doctor of the Church no mention was made about it on the Sunday on which the honor was bestowed. I was very disappointed, but I have since realized that the celebration of Sunday Mass has primacy over all other celebrations, no matter how good they may be and no matter who has just be elevated to the altar or given special honor. If your parish doesn’t have anything planned for DMS, you might want to see if another parish in your area plans on having a special celebration sometime in the afternoon–this is for next year, of course.