Sorry I meant to write rclone serve http but you seen to have figured that out.
It looks like it could not fetch this file
https://dd.humtv.net/humtv/2022/04/05/85f91a13d21c9f0003fa960a5ded69fa/master.m3u8
Is it supposed to be reading that from the rclone serve http? How did you set up the proxying and rclone serve http?