This script open all videos on the developer.apple.com/wwdc/videos page. Put these two files in a directory called WWDCAccordionSmash.safariextz, and open in Safari.

break_accordion.js

var listItems = document.getElementsByClassName('session');

for (var i = 0, max = listItems.length; i < max; i++) {
    listItems[i].classList.add('active');
}

Info.plist

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>Author</key>
	<string>Patrick B. Gibson</string>
	<key>Builder Version</key>
	<string>8536.30.1</string>
	<key>CFBundleDisplayName</key>
	<string>WWDC Accordion Smash</string>
	<key>CFBundleIdentifier</key>
	<string>org.fadeover.org</string>
	<key>CFBundleInfoDictionaryVersion</key>
	<string>6.0</string>
	<key>CFBundleShortVersionString</key>
	<string>1.0</string>
	<key>CFBundleVersion</key>
	<string>1</string>
	<key>Chrome</key>
	<dict/>
	<key>Content</key>
	<dict>
		<key>Scripts</key>
		<dict>
			<key>End</key>
			<array>
				<string>break_accordion.js</string>
			</array>
		</dict>
	</dict>
	<key>Description</key>
	<string>Opens all the video list items on the stupid WWDC videos page.</string>
	<key>ExtensionInfoDictionaryVersion</key>
	<string>1.0</string>
	<key>Permissions</key>
	<dict>
		<key>Website Access</key>
		<dict>
			<key>Allowed Domains</key>
			<array>
				<string>developer.apple.com/wwdc/videos</string>
			</array>
			<key>Include Secure Pages</key>
			<true/>
			<key>Level</key>
			<string>Some</string>
		</dict>
	</dict>
</dict>
</plist>