Thanks a lot musikbear for your suggestion.

I have converted the video from your suggested site. Also, I have found an article that is helpful to solve the issue.
Actually, I use VLC player and this post helped me a lot to solve the problem properly. Thank you

Hello everyone, Recently I have downloaded a video from a specific site. It downloads the WebM format. But the issue is I could not convert it to Mp4. Does anyone have any idea how to convert it to Mp4? Any suggestion would be greatly appreciated.