Mall ads.

Nice space if it was used to its fullest. 

Follow-up: I was back at the mall the next day (I failed to reach my goals the night before) and looking at this escalator again. Seems like a great place for a shoe or sock ad, since that's the part of the people the ad takes up. A string of shoes going down would be funny, especially when people lined up with them. It'd be a great ad for a store in the mall but maybe an even better ad for DSW, to drive people out of the mall to a free-standing store.

You could do the same with clothes, if you covered the window portion instead of the bottom area.