SD card won't download movies

[AC Question]

I have a 16gb sd card inside my phone samsung A5 the first gen. The problem is when i tried to download some movies around 1.6 gb it goes instant failed but it worked when i tried to saving it to my internal memory work so smooth but after that i tried to moving it to my sd card it's a no go it didn't say anything but "can't move the files to sd card" something like that