Animation render frame pixelation

[JasonWD]

Heres a quickie...
... anyone know why I get a lot of frames like this in an H.246 QT render of a quick and dirty solar study?

My work around was to render it as separate .tifs

I slapped the model up in 10min to show someone the effect of the sun on a proposal and it took longer to assemble the rendered .tif files into a video than the model took.