Pharmacist giving basic drug facts. It's pretty dry, image of the yucky scary leg injury notwithstanding:
Symptoms of an overdose: click here.
General information: click here. (Check out the "Effects" and "Addiction" sections, especially.)
and here's a huuuuuuge list of signs of a morphine addiction.
The videos I've found of people high on morphine have been of really poor quality. They're usually in hospital a hospital bed dealing with a traumatic injury or cancer and are using the drug properly, to relieve their extreme pain. I would think that morphine effects a person not in pain a little differently.
I'll be on the lookout for something more visual to show, but I hope this is a useful start for you.