What are D+ & D-?
Neopixels are dead simple to connect.. (not sure of the issue)
1.) If powering it form USB.. you probably do not have enough current..
2.) You only need to connect 1 wire the Arduino boiard of your choice.. the digital I/O line.. the +5v should come from a REGULATED +5v power source.. (usb may work with a handful of leds.. but not a full strip I doubt)..
3.) GND should be the GND used by the battery source and also shared with the Arduino.
It also doesnt look like you have the resistor on the I/O pins fromt he Arduino.. nor any CAPS on the power lines for the led strip.
It is recommended to do so.
Post a schematic or a hand drawn wiring diagram on how you have things set up.. nobody can tell form the shaky video.
Also,....that soldering looks a mess.. perhaps clean it up.. or try with one strip at first.. then daisy chain on the others?
Could just be a bad (cold) solder joint..