The "V" signature they discuss is actually an inverted V, kind of like ^. In the tropics, low pressure troughs and the winds around then result in kinks of the typical east-west flow pattern. Given that the flow around an area of low pressure is cyclonic, you get a northward component to the east of the wave axis and a southward component to the west of the wave axis.

The easterly trades also help at least partially explain why the southern side of the circulation is the last to develop for most systems; it is working against both the trade winds and the storm's motion.

The feature being discussed along 20W/21W is an unusually active tropical wave for this time of year. The GFS in particular is bullish with this wave in terms of development, but all too often last year it was bullish on many waves. If all of those features had panned out, we would've seen about 35 named storms. Anyway, it bears watching, but likely will not develop until the Caribbean -- if at all. It is extremely rare to see something east of the Lesser Antilles in the month of June, so it has that working against it.