How does the bifilar pendulum works

In bifilar pendulum the same weight as in regular pendulum is suspended on two strings or filaments ("bi" means "two" in Latin; "filar" is of the same origin as "filament"). It the weight sizes are small compared to the sting lengths, then it's more or less the same as regular, one-string pendulum. If not, it may be different in terms of motion equations.