"doesn't seem to work" is always a poor description. Can't you control the player? Do the leds not work? Something else like not compiling?
It complies, but I get the same colorwipe warning message that you mentioned. The changes you suggested worked great with the first DFPlayer sketch I posted. I made the same changes for the Pit Droid sketch and it did not work. Meaning, no sound with motion. However, I only had the DFPlayer and motion sensor connected. I did not have the neopixel connected.
I do get warnings when I compile.
I noticed if I change the 300 to a 100, the warning goes away. I have know idea what that means as I am just a beginner with Arduinos. I copy what I see and it usually works. If it doesn't I haven't learned enough to trouble shoot the code.
colorWipe() takes an uint8_t as the second argument (wait); 300 does not fit in that.
2. The description for below is not quite correct; due to delay(0) in the function, it might look like all leds change colour at the same time.
I am sorry, I really don't know what any of that means. However, yes the LEDS all change at once.
I did receive a regular Nano in the mail last week. All I did was swap the nano every out with the nano and the original Pit Droid sketch worked perfectly. Lights came on and sound played on motion. Although I would really like to learn why it did not work on the every and how to modify the sketch so that it does. I ordered an another DFPlayer and Neopixel for me to test. You gave me a good starting point with SoftwareSerial not being needed.