This well-done video provides an in-depth explanation (in French) and depiction of the recent celebration of Carnaval in the Basque Country.

The celebration, also known as Mardi Gras, takes place right before the 40 days of Lent in the Roman Catholic calendar, a period of self-denial and repentance of sins. Lent, which starts on Ash Wednesday, represents the time of suffering of Jesus Christ, before he dies on Good Friday and then rises from the dead on Easter.

Carnaval is a world-wide celebration, where people are allowed to enjoy life intensely because they are entering this period of deprivation. Participants typically wear masks to indicate the break from normal day-to-day life. The Basque celebration also includes dancing by characters that represent the evil in the world. In the video, there’s a burning of a character (St. Panzar) because he represents all that is bad in society.

Wikipedia has an interesting description of this international celebration and its possible pagan origins.