This site seems to be one of many which block some Tor exit nodes. The best solution in this case is to try another one using “New Tor circuit for this site” under settings or the relevant keyboard shortcut; Ctrl(or Cmd for Mac) + Shift + L. I was able to access the site after trying a few new circuits.
It may be just the exit node you get. Yesterday I tried and got lots of captchas but got in. Now I got in from a DE node. Had nothing to submit but was able to click all options.
VT is not just informal, you can upload stuff and check URLs. Even if you do not upload and only search for samples you are able to trigger a re-scan of the file which is presumably consuming resources on the side of VT.
After forcing a new Tor circuit and retrying the VirusTotal page for a couple of minutes, you will probably be allowed to view the page, upload your file, and then be subjected to another couple of minutes of mindless captchas. VirusTotal is a subsidiary of Google, and no Google site I have found has been Tor-friendly.
I have had a much better experience with Hybrid Analysis:
Yes you can by putting ExitNodes {??} in your torrc file. Replace ?? with any ISO TLD which has exit nodes but it would be the same as doing it in the browser. No guarantee you get a clean node without an abuse record.