I just saw their new video, it's so not "purely made by them" lol. Fair enough that it's not as scripted as their previous ones and do seem like "self-filming" during some of the shots, but it's so obvious that experienced/specialised people were involved in the filming. That said, I do think it's a really fun video though.

Tbh, I think they make better videos with smaller budges if their later videos are anything to go by. I mean, they went aboard to shoot the WMJB video, yes there was the sea and beach, but the video feels really boring and lazy, they basically just jump around on the beach and... that's it. Whereas in their later videos (One Thing, Kiss You) they actually seem to put in some effort to "act".

Well, I agree that it's not all self-filmed, especially when the 5 of them are onscreen.
But considering that they still have a filming crew with them for the movie, I thought that maybe they used that one when needed? Or they hired 3 guys to take along to film random bits to put together later, no idea.