As far as I can tell (and for $30 a 100 I think I might buy some to play with) they are claimed to be similar to the WS2811 (except with red and green swapped according to
http://surrealitylabs.com/2014/08/playing-with-the-pl9823-f5-a-breadboardable-neopixel-compatible-led/ )
the WS2811 recommends a series resistor bypass capacitor because "We require, in order to prevent power spikes phenomenon and power reverse polarity, series a not more than 100ohm resistor at the po-wer supply pin(VDD). The capacitance 104 as bypass capacitor." which reading between the lines and based on a few comments elsewhere on the web means these things can generate a bit of noise on the power supply so a series R and a parallel cap is advised to suppress this noise.
https://www.adafruit.com/datasheets/WS2811.pdf