Fan Keeps Turning On

Video in particular uses a lot of processing power which in turn generates heat.

See this document for guidelines and tips about maintaining a reasonable operating temperature of Mac notebooks

'Keep your Mac notebook within acceptable operating temperatures' - https://support.apple.com/kb/HT201640

In context - the uninstalling of the AntiVirus Software was a good suggestion. Even better was Removing it for the reasons provided by earlier person making that suggestion.

There are no known Viruses in the wild that self replicate and affect macOS. There are Malware and Adware that does affect macOS and are often times downloaded as part of an Application from Third Party UnTrusted Site and get installed along with the Application.

Effective defenses against malware and other threats

The MBA is a good machine but does have limits for perhaps your purposes. Open the Activity Monitor residing in Other Folder and once open >> View >> View ALL processes. Look in the CPU Tab for unusually large CPU usage and do the same in the Memory Tab for High Memory Usage. This will help identify what Process is using both CPU and Memory

If you installed any anti-virus apps, cleaning apps, or third party security software, then these types of apps can make your Mac work harder and generate much more heat plus cause slow downs. If you have any of these types of apps installed, then uninstall them by following the developer's instructions since these types of apps are not needed on a Mac and usually cause more problems than they solve.

You can also run EtreCheck and post the report here using the "Additional Text" icon which looks like a piece of paper.