Ben Judkins has a great write up on the context of this film! Many of us have seen the last few minutes of it completely out of context (starting at 11:43). The whole thing is fascinating. If I was teaching a class about my book Possible Origins, this would be a great film to show and discuss.
Do read Judkins' commentary, I just have a few things to add.
Gamble worked for the YMCA in the 1930s, long after the values of the YMCA had become Chinese state institutions. He is curious about Chinese religion and theatricality in a way the foreshadows Taiwan's role in preserving Daoist and other Chinese Religious culture. The earlier generations of YMCA men and women were openly anti-theater and local religion, but by 1930 those early advocates for the end of foot-binding who built hospitals and schools were his grandparents age.
This is an amazing document. The state had control over all publishing in China during these years, and used that control to imposed the YMCA Consensus. Which was the insistence that all martial arts had to be pure (jingwu), that is, without any theater or religion. This document shows that the suppressive effect may have been limited to urban areas. That suppression wasn't fully implemented until the Communists took over, sometime after 1949.
I don't have enough information about this ritual to say for certain what it is, but it looks like the creation of a canonization platform or "palace in the sky" which comes from the play Fengshen Yanyi (Canonization of the Gods). In the play, dead leaders from both sides of an epic battle become hero-gods when they arrive at the platform. The five tigers are part of the story, and they also represent the five barbarian kings who define the borders of the timeless (xiantian) Chinese kingdom. "Tiger" is a hominem for "barbarians," so it has both meanings.