How to export AviSynth project to video file?
Forget about output filters.

Use FFmpeg  (Linux, Mac, Windows) with this simple command

ffmpeg -i your_avs_file.avs  output.mp4


(or output.avi, output.mkv, ...),

or any conversion program which accepts .avs files as input, e. g. Any Video Converter Free (for Mac and Windows).



Note 1:

The Windows link points to the site for downloading Zeranoe's FFmpeg build. Unpack the downloaded file and use it — no installation is needed, perhaps only adding the path to ffmpeg.exe into your PATH environment variable.

Note 2:

If you want build FFmpeg by yourself, don't forget add --enable-avisynth option.

Note 3:

You may directly play back your AviSynth script files (.avs) with some Media Players, e.g. with Media Player Classic.