Answer:
First, never download software or videos from untrusted websites, as they can hide malicious code inside it. Never turn off the anti virus, anti virus only purpose is to block malware or viruses if you disabled it and don't know what you are doing high chance there will be a back door created in your PC. Try a antivirus that is well known and has good reputation on protecting a PC, note that good looking GUI on an antivirus doesn't tell it is always good, it's not the GUI you care about its the whole protecting your PC.
