Heya! I was able to get your “not working” file to work. I suspect the issue is related to how and where Blender stores certain data, like paths, but honestly, that is beyond me. I just know that sometimes you have to delete things in a certain way or else it seems that data can hang around and muck up other stuff.
What I did was go to the constraint and delete the driver from the purple bar, turning it back to blue. Then I proceeded to recreate the driver from there as shown in the video. The key seems to be ensuring the driver is completely cleared from the constraint (blue bar).
Here’s the new working file. It’s a 4.1 file so also be aware that under Edit Property the Type needs to be set to Integer instead of Float for it to act like a switch. In the video (2.8) he does this by setting the appropriate values to integers instead of floats but in 4.1 it’s more explicit.
https://drive.google.com/file/d/14nRxBGrr9aF0I2tdNOwA0QTKlPkEGDQD/view?usp=drive_link
Hope this helps!
