After a while it’s actually easier to use the numbers. There’s some memorization involved, but really, you’ll mostly use it for the 1-4-5 chords. So, for example:
1 - 4 - 5
G - C - D
A - D - E
Bb - Eb - F
C - F - G
D - G - A
You’ll get to the point (if you’re not there already) where you can hear which one of those chords are being changed to. You may not even know which key the song is in, but you can hear the relative chord changes and know “Oh, that just changed to a 4.” Not all of us are blessed with perfect pitch like Ben. That’s why he makes the big bucks.