according to the wayback machine the video's title was 【東方二次短編】いざよいさんの聖夜戦争【+C91CM】if anyone wants to try and find it again. I remember seeing it a long time ago. It was really fun.
Of course Saber is getting ready to eat or in the process of eating something. Honestly I don't think there is that many comic panels in which she isn't doing so.
As for Mary, I guess this is some sort of payback for trying to disrupt the one time where Saber was the focus and not eating, with food.
