It's a cultural thing called Fastnacht. Depending on the region of Germany, there are different traditions. In the Video you see a part of the schwäbisch-alemannische fasnet.
The Season kicks off on the 11th of November 11:11 and last till "Aschermittwoch" which is the beginning of the christian fasting period. It normally is 46 Days prior to the easter sunday. As the easter sunday is movable to the moonshine the Aschermittwoch is aswell. Look it up on Wikipedia.
What is seen in the video are processions to get rid of the "bad ghosts" of winter time and to welcome spring. The witches are groups of people who symbole happenings and mystical creatures from the area.
The witches "kidnapp" girls, paint their faces with ashes und steal their shoelaces to add them to their costums or sticks (kind of like girls getting "jewellery" on mardi gras). Sometimes girls are also stuffed into cages and carried for a time during the procession.
Hope this may help you.
