The Bun Festival is local to the island of Cheung Chau only. Pak Tai, the Taoist God of the Sea is worshipped and evil spirits are scared away by loud gongs and drums during the procession.
The celebration includes Taoist praying, opera performances and ends with processions performed by children dressed in colorful costumes.
Bun towers USED to be built 60 foot high piled with sweet buns normally outside the Pak Tai temple. These buns are supposed to be blessed and people would climb them to grab buns off them at midnight on the first day of the festival. This was supposed to pay homage and appease the ghosts of those who died in the 19th century plague that attacked Cheung Chau.
Except in 1978 a tower collapsed and injured 96 people. Since then the towers are built but for display only and are made in shops and delivered to the people who participate. But this is Hong Kong where you can buy them instead.
Cheung Chau before hand will go vegetarian for 3 days before the procession, no meat none at all will be eaten served on the island not even the McD's you see immediately off the ferry. Nothing none nada (it often closes).
The procession is the biggest most important part of the festival and each sort of group of houses on the island will build a float of some kind and children will sit atop of them TCG does not know the significance of this.
You can find more videos here again TCG is not from Cheung Chau or from a family of fishermen and therefore does not observe this holiday.