No. Mozilla's Auckland office has other engineers working on Gecko video playback.
I know of at least one other NZ Mozillian (Nick Cameron, on the Rust project) but I'm not sure if he works remotely or at an office.
There were about ten NZ Mozilla employees when I worked there a year ago. Not all at the Auckland office but there were plenty there to keep the office utilized at the time.
Pretty sure he lives in Wellington and so must work remotely.