Archive.org experienced an hour-long outage due to tens of thousands of requests per second launched from 64 virtual hosts on Amazon Web Services, which brought the site down for all users.
Engineers scrambled on a Sunday afternoon on a holiday weekend to work on the issue, and the site got back up by blocking those IP addresses, but another 64 addresses started the same type of activity a couple of hours later.
Those wanting to use Archive.org's materials in bulk should start slowly and ramp up, and if starting a large project, should contact the organization at info@archive.org to avoid overwhelming the site.