Videos of artworks are especially valuable for three-dimensional forms of art such as architecture or sculpture.
Here are two strategies for finding videos of artworks:
Strategy #1: Use Quest. On the left, under Material Type, limit your search to Audio Visual materials. (You may have to click Show More to show the Audio Visual limiter.)
Strategy #2: Use a video search engine to search for free videos online. I recommend Google Videos and/or Bing Videos.