(With nothing after the trailing colon.)It seems your Libav/FFmpeg (libavcodec) installation lacks the following encoder:
So what could I be missing?
More background: QuickTime no longer opens the .mov files that it used to convert-while-opening. I am getting the .mov files from other team members. The app MediaInfo reports that they have RLE (I presume run-length-encoded) video and PCM audio. Perhaps if I ask the animators to export in a different format? My alternative is to get a cheap, old MacBook and use the older tools.