You downloaded the wrong thing. You need to get the raw file: https://raw.githubusercontent.com/finefin/SD-scripts/main/multi_frame_render-bet...
Viewing post in (Beta) Multi-frame Video rendering for StableDiffusion comments
I did not change the log output at all. Maybe you need to update your SD install? I use SD.next by Vladmandic and don't have any problems.
You could try to comment out that function call on line 69: put a "//" in front of the line like this:
// shared.log.info (....
If you do that, you wont see any progress in the UI, tho.