In the past we would have used an eraser to put highlights on a gleaming surface like latex or leather pants for example. The question is if the eraser is the right tool to achieve the same result when it comes to digital drawing.
With a real eraser on real paper you had the advantage that the edges of the area were smooth. You could influence the look by putting more or less pressure on the eraser to achieve the desired result.
As you saw in the video the eraser isn’t the right tool if you want to have smooth edges rather than sharp between the surface and the highlights.
The better option is to use the dodge tool Manga Studio and other graphic software programs provides.
When using the dodge tool you have to remember that every time you make a new stroke (putting the pen on the tablet and lifting it up) you lighten the area up one more level. The intensity of this effect will depend on the setting for the opacity you have chosen in the tool options. Please let me know if this isn’t clear for you and I will provide another (shorter) video on this.
Have fun drawing and a great day ahead.