Repeat vieo for 1-hr, remove audio

ffmpeg -i input.mp4 -vcodec copy -an -stream_loop -1 -t 3600 -vf 'scale=1920x1080:flags=lanczos;split[original][copy];[copy]scale=ih*16/9:-1,crop=h=iw*9/16,gblur=sigma=20[blurred];[blurred][original]overlay=(main_w-overlay_w)/2:(main_h-overlay_h)/2' -o output.mp4
-c:v libx264 -preset slow -crf 21

Combine two files together

(echo file 'halo1.mp4' & echo file 'halo2.mp4' )>list.txt
ffmpeg -safe 0 -f concat -i list.txt -c copy output.mp4

Append multiple copies of same video to single video

ffmpeg -i splintercell.mp4 -c copy output.mkv
ffmpeg -stream_loop 4 -i output.mkv -c copy splintercell.mp4
del output.mkv

Strip sound out of video

ffmpeg -i analogue.mp4 -c copy -an analogue-nosound.mp4

Extra single audio stream from file

ffmpeg -i video-podcast-recording.mkv -vn -map 0:1 -acodec copy audio1.aac