I found the solution. Installing opera-ffmpeg-codecs from the herecura repository fixed the problem.
Latest posts made by shenper
RE: Can't play videos from Udemy and VimeoOpera for Linux
Can't play videos from Udemy and VimeoOpera for Linux
I can play videos from youtube, but when I try to play videos from udemy and vimeo (I didn't test other video websites) the video doesn't play. With firefox the video runs normally.
I am using Manjaro KDE.