he means don't render to .avi format from maya... it's a better idea to render out to an image sequence, because if you find an error you can just go re-render some frames instead of the whole thing, and if maya burps while you're rendering to an avi file you won't get anything at all or a corrupt file, but if it crashes while you're rendering to a sequence you still get all the files it DID finish before crashing. you only have to go back and render the ones it didn't get to yet.