That thread is quite old, but I'm surprised noone mentioned AVFS : you can avoid having to export a huge intermediate lossless file by opening the AVS script with Avisynth Virtual File System, which, as its name implies, will create a virtual uncompressed file in a "C:\Volumes" directory. It won't occupy significant space on the system partition (despite the huge size displayed in Windows explorer), but it will behave just like an uncompressed video file created with the same Avisynth script would : you can read it with a media player, or you can directly import it in any non-linear editing software. You may need to configure ffdshow for raw YUV footage to be recognized by those softwares (ffdshow video decoder configuration > Uncompressed video > toggle "all supported formats").
http://turtlewar.org/avfs/