The gull gets away in this case. From Meghan's tumblr blog:
"I've learned that this is the worst way to stalk a seagull. It's much safer and more effective for me to divebomb them in flight while they are pretty high up. That's when they are less likely to see me coming, and my higher terminal velocity takes them by surprise and breaks their necks. And I can easily pull up once I've got one.
"On the ground, or roof, they feel vulnerable and are more on the lookout for trouble. And I am way less maneuverable myself, and slower.
"So, the next image in this sequence is a really super awkward situation of me falling off my own roof."