Looks like ok.ru is not allowing download from ffmpeg. Optional parameter is required to pass a useragent string that is not the one ffmpeg uses (like chomes). Ill look at supporting in the next release.
Maybe you can revert it to the state of 188.8.131.52 as it works perfect there but ofc that's up to you.
I will happily test the new version when it comes out. Thank you for looking into this.