"Drifting" project photos while browsing instructables: bug? Answered

While browsing sewing projects I noticed that the main image for each project was "drifting" downwards and sort of slowly cascading down. I went to the next page of projects and after approximately 30 seconds the same thing happened again. On two separate days the same thing has occurred, on multiple pages. Is this some sort of ad related action, or is it a glitch in the site? If it is an ad, it is a very inconvenient one that makes it nearly impossible to browse your otherwise excellent web site. As a side note, if you follow the pictures as they fall and click the picture it will take you to the right instructable... sometimes.