I just discovered that it's possible - actually already for quite a while - to not only link to the start but also to a specific point within a youtube video.
Let's take as example the URL of the following video clip:
The intro of this song takes 2 minutes and 59 seconds. Then the main part of the song starts. What we only have to do is to append #t=2m59s to the URL:
Now this URL directly points to the main part of the video clip.