That'd be Video Toasters. But Newtek ditched Amiga support in '95, and by late 90's PCs or DEC Alphas would cream the Amigas for the render farms.
Even Babylon 5 switched the render farms for seasons 4 and 5.
Not impossible someone would still want to replace individual systems in a render farm rather than upgrading, but given the potential speed gains it'd seem like a poor choice.
(I think this is a subset of your comment rather than an extension but Babylon 5 reference ;)