The electrical tape's there to help make the join between the handle pin and the belly a bit more secure, and also to give it a bit more springiness and help even out the taper when you drop strands out.
Leather whips have bolsters between the braided layers that do the same.
I've been following those directions (kind of - I'm making a stockwhip instead of a bullwhip) but I cut the core strands a bit longer and braided them together into a 4 strand braid until I dropped the first strand.
That was mainly because I thought it'd be easier than keeping them all lined up next to each other while I taped them up

We've got just over 2 full weeks until Play - I reckon you could have one braided by then
