https://support.virustotal.com/hc/en-us/articles/4413290242705
WARNING! These are the options enabled by default when installing VT4Browsers for the first time, please take a close look:
Scan downloads. The extension will automatically submit to VirusTotal any files that you download that are not filtered out by other more granular settings. For non-executable files a prompt to confirm the upload will be displayed.
Don’t scan documents. The extension WILL NOT automatically submit to VirusTotal any documents that you open or download (DOCX, DOC, XLS, XLSX, PDF, etc.).
Send anonymous passive DNS data. The extension will share with VirusTotal domain name to IP address mappings for any DNS resolutions that your browser performs. VirusTotal WILL NOT link these resolutions to your user or any other piece of information that could identify you. ..