Yes, effect is 100% rendered in Final Cut: I checked the sequence where it is and it was rendered there. Also the final sequence (made of two sequences – intro and one with film inside which is this clip) is also rendered.
Also, I can’t remember did I mention this, but when I started my computer today I decided to try to export only that clip with few seconds before and after from the main sequence and it worked. Then immediatly I started to export the whole final sequence, but once again it didn’t export that clip (again – all black on that place).