QuickTime Player unknown error -70172

I've record some video lately with an old camera, and it convert to a AVCHD document. At the first few day it works perfectly, but one or two week later it automatically get upload to my iCloud. And after I download it back some of my longer files can't be open. When ever I try to open the files a window pop out and say Can't open the chosen file "BDMV." Unknown error -70172. And when I try to export the whole file to google drive it upload 106 of them, but I can only view 56 of them.