A video on Russian social network VKontakte has been causing iPhones to crash. The only thing you can do is force a hard reset on the phone by pressing Home and Power buttons for a few seconds. The good news is that the attack does not appear to be permanently harmful. There is clearly something odd about the videos codec that is causing a bug in iOS code to rear its head. But that doesnt mean that the same technique could necessarily be easily used to spread malware.”]
Source: https://www.bitdefender.com/blog/hotforsecurity/watching-a-video-can-crash-and-freeze-any-iphone/