To convert videos from web to mp4 and decrease frame rates, we can use the command below:
ffmpeg -r 5 -i Videos/Screencasts/tutorial.webm -c:v libx264 -preset veryfast -c:a aac -vf "crop=trunc(iw/2)*2:trunc(ih/2)*2" Desktop/tutorial.mp4
To install ffmpeg
sudo apt install ffmpeg