When she linked to the video it made me wonder if this is a common thing. I did some looking around online and it turns out this is a fatal flaw in these Droll Yankee feeders. Here's another squirrel that has figured it out.
Here's my original video for reference.
All these squirrels raiding feeders got me thinking about this old clip from a BBC show where they set up an elaborate obstacle course for squirrels to see what lengths they would go to for food. Have a look.
I'm thinking it would be fun to set something like this up some day in my yard or at work. We're feeding the squirrels anyhow, might as well make it interesting.