FFmpeg

Change video speed (2.0x):

ffmpeg -i input.mkv -vf "setpts=(PTS-STARTPTS)/2.0" -af atempo=2.0 output.mkv

Change container from MKV to MP4:

ffmpeg -i input.mkv -codec copy output.mp4

Record RTSP stream w/ hardware acceleration (NVIDIA):

ffmpeg -rtsp_transport tcp -i rtsp://10.0.0.1/ -c:v h264_nvenc -preset fast -b:v 1000k -c:a copy output.mp4

Download a portion of a video using yt-dlp and ffmpeg:

yt-dlp --external-downloader ffmpeg --external-downloader-args "ffmpeg_i:-ss 00:01:07 -to 00:01:13" -f best https://youtu.be/LR6KIFIJwHU -o "output.mp4"