YouTube - If you navigate away from a video, then immediately return, the player continues where it was left off.
YouTube - Clicking on the “Report” icon on YouTube stops the video if it’s currently playing.
Youtube - The settings icon spins when you change quality of the video until it stabilizes.
Apple - When watching Apple’s tutorial videos about iWork, each completed video gets a checkmark next to its name.
Vimeo - When clicking play, the site will scroll up to fit the video in the browser window.
Vimeo - When visiting a non-existing page on Vimeo, the title is VimeUhOh.