Depending on the car this can be okay or bad. I wouldnt try that with the Escudo for example.
The video is giving good advice when tuning for performance.
Mostly when tinkering with the transmission, I am more concerned about making it more fuel efficient without losing too much of power, of improving traction when accelerating out of corners, but that is a result of basically only driving events where fuel is a limiting factor, or for some cars that really want to spin the wheels in the lower gears.
You set gears based off grey Line on dyno chart. In garage setting in home. This will proved information for HP and TQ peak numbers. From there you can set first gear and have a long second gear before subsequent gears after peak tq. It can get tricky.
I provided examples. If grey drops dramatically then it’s best to use low gear ratios or (1.211:1). It has a steady decrease in high rpms. It’s best to use high gear ratios or (0.881:1). You set your final drive based on how well the engine produces torque or for your personal needs in performance such as track usage. Again it can get tricky.