How to create fast forward (timelapse) video from normal one with ffmpeg without audio:

# ffmpeg -i crap.mov -an -vf setpts=0.20*PTS crap-fast.mov
NOTE: If you want to create the video with sound (remove the -an option), and the encoder is "aac", you must add the options "-strict -2".

How to create a slow motion video from normal one with ffmpeg without audio:

# ffmpeg -i crap.mov -an -vf setpts=2*PTS crap-slow.mov
NOTE: If you want to create the video with sound (remove the -an option), and the encoder is "aac", you must add the options "-strict -2".

More to read about slowing down or speeding up the video, here.

How to join multiple videos together:

1. Create a text file with all their path in it:
$ for vid in $(ls *.MOV); do echo "file '$vid'"; done >vids.txt

$ tail vids.txt 
file '01170531_2651.MOV'
file '01170532_2652.MOV'
file '01170532_2653.MOV'
file '01170532_2654.MOV'
file '01170532_2655.MOV'
file '01170533_2656.MOV'
file '01170533_2657.MOV'
file '01170533_2658.MOV'
file '01170534_2659.MOV'
file '01170534_2660.MOV'

2. Execute ffmpeg as follows:
$ ffmpeg -f concat -i vids.txt -c copy video_draft.mov

How to add watermark to video with ffmpeg without loosing quality:

$ ffmpeg -i video.mov -i watermark.png -filter_complex 'overlay=1400:830' watermarked-video.mov

How to remove the sound of a video with ffmpeg:

$ ffmpeg -i video.mov -vcodec copy -an no-sound-video.mov

How to rotate video with ffpmeg:

$ ffmpeg -i video.mov -c copy -metadata:s:v:0 rotate=90 video-rotated-90derees.mov

How to change the frame rate of a video with ffmpeg:

$ ffmpeg -i 256fps-video.mov -filter:v fps=fps=60 Result-60fps-video.mov