I do a no-keg version of this-- mostly just to save trash from the plastic bottles or club soda cans-- and you can get it really fizzy, which I love
I’ve simply got a big 20lb CO2 tank, with the regulator similar to the one in the video which goes into that ball lock adapter. But instead of the keg I use a carbonation cap with diffusion stone which just screw into your plastic soda/sparkling water bottles.
I’ve got two of those carbonation caps-- permanently on two 2lt plastic bottles, then as one finishes, I refill, hook it up to the ball lock, turn it on, shake it to help the diffusion (or just leave it until I remember to unhook it).