Honestly.
I'm getting this every time I play Nekodancer.
Whenever a new song plays, the "Easy" banner comes down. Normal, ok. But, as soon as the banner comes down near the arrow silhouettes, it freezes, and so do the arrows. I can still move around, etc etc, but I can't do anything.
If anyone has the same problem or has a solution, tell me ASAP.

Have you ever tried switching browsers?
Don't use Firefox

i think it might be the video player issue with firefox

This happened to me while on Firefox.
I suggest switching to Chrome if you have it.

Thanks guys! I was using FireFox and when I tried it on Chrome it worked. Thanks! ^^