Mencoder: Change speed and size of movie and output such that Quicktime can play it

mencoder input.mp4 -speed 0.33 -vf scale=450:360 -ovc lavc -ffourcc DX50 -oac pcm -o output_slowmo_small.avi

The -ffourcc DX50 makes it quicktime playable
The pcm is needed when we change speed (copy won’t work)