simple audio input for arduino

That is pretty cool looking, ive made a single row / double row of 12 leds's for a volume level.
First place i would check is the code, maybe try and ask the person in that video or others like it for their code.
Double check your resistors that their the right value, a quick check is by just visually checking color values.
The only issue I had is that mine would get stuck at a level like half way up(and halfway up would stay light up even with volume down or stereo of even a reset would not fix, I had to disconnect power), or if i maxed it out, it would get stuck their also, I fixed that, with a resistor across the +/- input. but again i was only using 1 or 2 rows of leds, When I did make another row, and used a crossover from a speaker box so i had a 2 rows lows and mids, and if i had enough parts, i could have used the Highs as another row aswell, but that only gives 3 rows.
For yours Im not sure I would suggest you post your code, and someone may notice something, a simple extra space somewhere, or a wrong value can still compile, but give strange results. Hope this helps some or at least gets you thinking?
Good luck.