Download 3 videos concurrently using youtube-dl.

youtube-dl.sh

#!/bin/bash

i=0

while read LINE
do
    (youtube-dl $LINE -o "%(title)s.%(ext)s") &
    let i++
    if (( $i % 3 == 0 )); then 
        wait # Limit to 3 concurrent subshells
    fi
done < $1