My wife and I watched this video the other day. She could make out a little of what they were saying.
It's a fun video but I won't listen to it with any regularity on headphones. It's not as bad as rappers who mumble alot (southern rappers looking at you) but not my favorite
This is a new-ish sound which started from British/UK rap(and UK grime). Here's an example:
East coast US rappers adopted it and made their own slight variations which spread to other states. Here is an example of Drake trying the flow/style:
It might not sound like it at first listen, but this is much, much better than the mumble rap of the 2010s, which has been mostly left behind(and thank goodness for that). I just consider it to be faster-paced rap/hip-hop and it has slowly been morphing into a sort of house/techno/rap mix lately:
(I could picture this song in a racing video game like Midnight Club of NFS Underground).
On a side note: It's a shame that Eminem didn't try this style. Here's an example of how he would have sounded with it.
I can't usually stand anything modern, but I enjoyed the video and it didn't go so heavy into the elements that grate on me the most. Maybe I was just distracted by the video and it not taking itself seriously.