Why can't Apple's SMS video be opened?

Probably because the phone cache crashed too much.

Most of the reason is that the mobile phone cache crashes too much. Press and hold the Home button and the power button of the mobile phone until the Apple logo appears, and then release it, and forcibly restart the mobile phone to recover. 2, in daily use, don't open too many background programs, double-click the phone's Home button, slide up to close the programs running in the background of the phone, time switch machine, you can clean up the phone's cache.