A five-second video being shared online as a prank is causing Apple devices to slow down and eventually become completely unresponsive until a hard reset is performed. The glitch was showcased by EverythingApplePro in the video embedded above and appears to affect iOS versions from 5.1 to the latest beta version of iOS 10. After performing its own tests The Verge mentions that the video appears to only crash devices when it's sent as a link rather than simply transferred as a file.
The only way to recover from the crash is to hold the power button and home button at the same time for several seconds to perform a hard reset. It should be noted that a hard reset will not alter anything on your device, the iPhone will work as normal once it has rebooted this way.
Currently the top level domains hosting the video appear to be vk.com and testtrial.site90.net, though it could be hosted anywhere really. The bug isn't believed to pose any security threats beyond annoying victims that fall for the prank, although for obvious reasons we're not linking to the video.
Vulnerabilities like this have surfaced in the past although Apple is usually quick to issue a fix. Back in 2015, the infamous "effective power" bug took the internet by storm, as it was discovered that a specific string of characters sent via text message to an iPhone would cause it to reboot.