I think the best introduction to this YouTube video is to quote the text posted alongside it:
The following clips were captured at Corpus Christi Catholic Church in Aliso Viejo, California. The parish bulletin encouraged parishioners to wear Halloween costumes to Mass. The segment includes Eucharistic Ministers dressed as a huntsman and a devil, as well as an organist dressed as a devil. The 6 min clip ends with Fr. Fred Bailey leaving before the end of Mass, returning shortly thereafter in his "Barney" costume.
There's also a witch singing the responsorial psalm, and there's also the immortal line, "As goblins and ghouls, we raise one voice: Our Father, who art in heaven…" As for Barney, the Rev. Joseph R. Chambers fingered him as a creature from "the world of demons and devils" back in 1993.
Not being a Catholic, nor a Jack Chick-besotted fanatical anti-Catholic, nor even Tim Cavanaugh, I have nothing substantial to say about this. But as an aficionado of anything soulful or strange, I have some sympathy both for whoever thought up this brilliantly deranged Halloween mass and for the traditionalists who have wondered whether it "make sense, to shut down and harass those who express traditional forms of Catholic worship while tolerating this type of strangeness."