Taking your example video this is convert a p/line to a drainage pipe written for civil road works, with most common AUS sizes. Needs linetype Equal the length of dashed is set to 2.4 which is a length of a concrete pipe. Handy for civil works. It is not dynamic.
*EQUAL,_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _
A,1.0,-1.0
Pipe offsets.lsp
If you post here a VLR function can test.
Fillet offset circle.lsp
Have a look at "Fillet offset circle" uses reactors.