Kindly suggest a good free audio and video screen recorder to create tutorials. CamStudio installer for the official site has been detected as containing virus by AVG AntiVirus.
CamStudio (at least as downloaded from Sourceforge) is awesome and not malware. Jing is also very good, albeit limited in some ways. Depending on what you are doing, TeamViewer may also suit you - it records very well, but only from remote computers (you could use a virtual machine to simulate that).
How to Record Your Desktop to a File or Stream It Over the Internet with VLC
It looks like it is getting flagged because it contains or uses InstallCore for targeted advertising - most likely within the application itself. During installation of the software, you should be able deselect the option to install the InstallCore module. You could also proceed through the entire installation, then use AVG to remove the InstallCore components.
Or you can select another program from the AlternativeTo database.