So I just found out recently that my Samsung Galaxy S2 has FAT partition. I was confused at first because I was surprised why I could not copy a 5GB file to my phone. I thought there was some problem during the download.
I tried to re-download the file again (yes, I wasted bandwidth by downloading it all over again) only to see the same result again. I was clueless so I searched Google why this is so. Turns out that FAT partitions cannot handle more than 4GB of data.
It had been a long time since I encountered this situation so I totally forgot about this one. Tsk, guess the manufacturers did not want to use exFAT (extended FAT) or else they probably will have to pay Microsoft more patent fees.