I think he has slightly misunderstood, or at least misstated, the physics:

> a pendulum oscillates is only determined by its length (and the strength of gravity), while the weight at the end of the pendulum’s rod (which clockmakers call a bob) doesn’t really matter.

This not correct. The period is determined by the distance from the fulcrum to the centre of mass. The position of the bob does matter. On my grandfather clock there is a small screw that adjusts the position of the bob and hence the length of the pendulum so that you can regulate the clock.