Trump Shooting Questions

It hasn't been easy either yesterday or today to find meaningful information of the details of the Trump shooting in Pennsylvania Saturday, but this is the most comprehensive summary I have seen:

Weird Things About the Trump Shooting

It is inexplicable why Trump was left so vulnerable to this gunman by security. Video appears to show that Secret Service snipers had the shooter in their sights but waited for him to shoot.

Waiting for any kind of reasonable explanation, let alone an official confirmation of what video shows.

And the lady behind Trump? What gives?