Can you make make me a little animation about the "projection to next point" with the "Helper lines" ?

I am a little perplexed about that!

When I use it (just for the fun because I have not yet understood really the power of that and how use it! )

I can't used the white point shown at the intersection of the Helper white line and a vertice of a volume : it's disapeared as soon as I move the mouse!

So a pedagogic video of that will be very helpful for me ...and surrely other people! :)

Have happy new year and coding!