The /* starts a comment and the */ ends a comment, so those lines around the fireworks code are just for highlighting the fireworks code, they do not comment it out.
I presume your brother is using a Teensy?
If not what memory values does he get when he compiles? Is he running out of memory?
It runs perfectly for me here.
You could run it up on your matrix easily enough, just change the sizes and change the cLEDMatrix parameters to make your matrix vertical.
I’ll have to ask him tomorrow, I doubt he is awake at 4am, lol. I could try running it on mine and see what I get, But I am unsure if it is because of the amount of led’s it is attempting to drive? I had the same problem when I was testing it out on the mega and the 8x32 matrix, for the most part I was able to remedy it by messing with the some of the variables, but still had the occasional freeze… I will see if I can convince him to fiddle with it a bit until he is satisfied it is ok. He is very concerned that somehow uploading sketch after sketch and the program freezing will fry the teensy… lol, silly brother.
Of course my matrix is 8x32 as well so I guess if there is a 256 issue I won’t be hitting it either. I did have a quick look at the code but didn’t see anything, it seems to deal with X & Y rather than an LED index.
On checking my code, I had left the height as 36 so even though I only had 32 physical leds it was still writing to 36 on each line. Really don’t understand why it is crashing for you and your brother.
46mhz non optimized? or maybe just some old libraries kicking around that are not doing their thing. I’ll try and flush it out when I wake up this evening.
Thanks again 
48MHz optimized.
Using TeensyDuino V1.22, Arduino V1.6.3 and FastLED 3.1 from start of July.
Does it crash completely? Or do his switches still work, like the heart switch?
I have no idea what is going on, I just uploaded it to mine and it works fine, 72 optimized, 72 non, 48 optimized, 48 non. … 11% program memory 5% ram. I guess I’ll just have to get him to mess around with it a little.
although I might know what is going on, it is probably a power issue, as to why this would consume more power than any of the other sketches I am not sure. I was having problems after I accidentally grounded out one of my data pins with some solder (oops, lol) my sketch would run for about 10 seconds and then the unit would freeze up. Only because I was pulling power from the unit itself rather than from an external supply, once I switched it my problem went away, but his is still pulling off of the units power rather than an external.
As a side note, I wasn’t going to include the fireworks on mine simply because I thought the lack of height would look silly, I have now reconsidered
When the fireworks explode, it does a white fill on all the LED’s. This will draw more power.
FastLED.showColor( CRGB::White);
//delay( 1);
FastLED.showColor( CRGB::Black);
In the Move function.
Ya my brother just confirmed my suspeciousin, he sent me a picture of where I soldered the leads on to, and it is through the teensy’s internal regulator which if I am not mistaken can only put out about 600ma. He also said that it only freezes when one explodes and flashes white, so you were correct as well