Android has more than one video-related security hole on its hands at the moment. Trend Micro has found a flaw that uses a malformed Matroska (MKV) video in apps or websites to crash Android's "mediaserver" service, effectively turning the target device into a paperweight. It'll not only render your phone's interface mostly or completely unresponsive, but silence all calls and notifications. You might not even get past the lock screen, if your phone is locked during the incident. An intruder could take advantage of this seemingly brain-dead state to hold your handset for ransom, threatening to shut you out unless you pay up.