Latest version breaks CSRF token of idp shibboleth servers. Impossible to use idp when plugin enabled.

Relatively useless:
Files are not uploaded already above a size of approx. 145 MB (File exceeds maximum size).
Furthermore, it would be nice if user-defined file extensions could be defined.
And the website behind it doesn't work if the options for "Improved protection against activity tracking" are exhausted in Firefox.

Error "Failed to communicate with VirusTotal" now. This was a great 4 1/2 star extension while it worked, although I supplemented VT4Browsers with Winja.

failed to communicate - does not work

I am given an error "Failed to communicate with VirusTotal" every single time.

It always display "Failed to communicate with VirusTotal".

Excellent concept, but the core function of the add-on no longer works on current versions of Firefox Dev.

Every function doesn't work (exept the scan of downloaded files), the result is always an "Error 404" page.
(I refer to "Scan selected link" and "Scan current page" functions)

"Error sending file error" for ages now, this is just bad advertisment imo (running the latest FF Quantum 67+).

Immer wieder "Error sending file error". Damit total unbrauchbar!

So far, all it has done is waste paper. With everything I print, an extra page prints with only "VTZilla 0% x" on it. There are no print setting in the extension. I can't find any mention of it on the internet and the Virustotal website contact page won't submit my issue. I did find that I could submit it in Chrome, which isn't good for a Firefox (56) extension. I'm waiting to hear from them but for now, it's costing me money so I have to disable it.

Initial review (v2.0.1):
This is a very handy extension, especially for users that prefer (and can afford to) take proactive security measures where possible.

To the developer(s): Consider changing the default settings in this new version so that they are more in line with what is stated in the privacy policy. Querying VirusTotal on every download should be opt-in, not opt-out.

Update (v2.1.1):
I see that you folks decided to change the privacy policy instead, so I guess my review was productive in a way. I can still recommend VirusTotal as a service for scanning files found in the net (because it can be very useful sometimes), but I will no longer recommend this extension.