Save screens in pwd of terminal
for i in {1..3600}; do scrot -d 3 '%Y-%m-%d-%H:%M:%S.png' ; done
This command convert images in pwd/directory/ to full resolution video (FPS = 30):
ffmpeg -f image2 -pattern_type glob -i 'directory/*.png' -r 30 -c:v libx264 -pix_fmt yuv420p out.mp4
For scale the video in output (keep aspect ratio so that height is adjusted to fit) use this (width=480px):
ffmpeg -f image2 -pattern_type glob -i 'directory/*.png' -r 30 -vf scale=480:-2,setsar=1:1 -c:v libx264 -pix_fmt yuv420p out.mp4