The structure of your presentation is not Beginning-Middle-End.
It's Beginning-Middle-Action. There is a reason those people are gathered (see 3, below). The action stage is to further that goal. Don't leave the podium, the room, the video camera until that goal has been progressed.
Fast-track your progress with the book.
Awesome Presenting 1: It starts with why.
Awesome Presenting 2: Don't blame PowerPoint
Awesome Presenting 3: Be Clear on the Goal
Awesome presenting 4: Think Movie
Awesome presenting 5: More Stories
Awesome Presenting 6: Brilliant at the Basics