Post twitter responses as comments

Hello. I’ve been asked to look into what plugin is being used on sites where Twitter responses to a specific post show up as comments, with a “This comment was originally posted on Twitter” notification. An example I was sent is this site.

I’ve been searching for a while, and I’ve seen a number of sites that seem to use this plugin, but I can’t find anyone who identifies what the plugin is. Any thoughts would be most helpful.

Thanks,
Jonathan