The problem is that what you copied-and-pasted isn't the complete link. When a link is really long, what is displayed on most websites is the beginning of the link and the end of the link with a ... in the middle. You copied that, instead of the whole link. If you see a ... in the middle of a link, right-click it and select properties to get the actual link.
On topic:
A comment on the YouTube video, presumadly from someone who has read the story, explained that the gun wasn't loaded and the man left a note to his mother saying that he did not intend to kill anybody.