I saw the wiki but have a single example:
Quote:
$regex(a cat walked by the dog,/cat|dog/g)
;'cat' and 'dog' are matched, returns 2


But that example, I can not understand in this code:
Code:
alias YouTube {
  if ($regex($1-, /\Qyoutube.com/watch?v=\E(\w+)$/)) {
    sockclose YouTube
    sockopen YouTube www.youtube.com 80
    ; keep the video ID for later on
    sockmark YouTube $regml(1)
    echo -a The video ID is: $regml(1)
  }
  else {
    echo $color(info) -aef /YouTube: invalid youtube link
    halt
  }
}


The line:
Code:
if ($regex($1-, /\Qyoutube.com/watch?v=\E(\w+)$/)) {


a)Why \Q ?
b) Why it that signifcan this: \E(\w+)$/)
c) What is the use of /g in the example above of wiki?

Please explain this whole line as simply and clearly, note that not mastered the English language.

Thank you.