Why are there non-standard altitude callouts?
From the same channel and also an A340 at 4:26 in this video the standard '100' can be heard.

The reason is a built-in timeout, if a certain time elapses between callouts—say due to non-standard [shallower] descent rate, perhaps due to high headwind for example—the current height is called out. In other words, you get to hear a callout at regular intervals.

From an A340 manual, here is the bit about the intermediate callouts:





Just a bit of history: one of the early TAWS systems (Mk II I believe) had a rising tone instead of the 100, 50, etc., you can watch it here.

Note on terminology: those callouts are heights (radio), not altitudes (barometric).