>>5920239
A couple notes.
webm-for-4chan doesn't normally use a resolution of 1920 for a clip of 1:30. It'll pick between 960 and 1024.
fps is automatically reduced based on clip length, there's usually no need for a manual override.
Audio under 80k is mixed down to mono, so it still usually sounds fine unless it's music or ASMR that relies on stereo effects.
There's a bitrate cap that prevents short clips from having an unnecessarily large size. It has to be over roughly 18 seconds for it to hit 6MB.