It seems the video was released eight months ago, and most likely filmed much earlier so it could probably be assumed that Covid was and still is a concern. The people we see are probably just being extra cautious, especially on public transport. That doesn’t feel like to much of a stretch as its already very common for people in Asian countries to wear masks in public for a variety or reasons.

They probably took them off in the apartment as I assume the host and bus driver were tested prior to filming, and they’re just making production easier.