No, based on their keybindings it sounds like they use dwm, a window manager which you have to compile yourself, configure yourself in a .c source file, and comes without window decorations by default, I believe. It's neat but made for 0.1% of computer users at most.

Although I want to add the "Windows Key + Left/Right Mouse Button" bindings are incredibly convenient and should be supported by every OS by default imho. The area you have to hit with the mouse cursor to resize a window turns from "a few pixels in the window corner" to "the entire damn window no matter if there's a button or not".

I use bspwm, which is still not easy for beginners though not as extreme as dwm, but it's also kinda besides the point which is that a lot of the complaints about borders really are complaints about the difficulty of moving and resizing windows or otherwise manipulating rhem, and once you look at it from that point of view there are alternative solutions, one of which is this one.

Pretty sure you can configure any WM to use those key combinations. I used them in i3 and currently use them in bspwm. Not sure why you jumped to dwm immediately.

I'm sure you can also use them in a fully fledged DE, and someone mentioned using alt + click on windows to drag.