For the interactive graphs, I think we should follow the standard set by the videos - show the graph with a gray-out (transparent?) effect, with a big "play" button in the middle. Once clicked, the graph becomes non-grayed (thus indicating that it finished loading), or we could change it to non-grayed on mouse over, and show a loading bar when clicked. Also, instead of the "play" button, we could experiment with a "gears" button, possibly even spinning ones. Once we have many interactive graphs, we could do an a/b test on this.
Yet, I feel we are ignoring a big class of interactive graphs that will suffer from this design - graphs that are useful in both the static and in interactive mode. For example, tooltip, budget, and crossfilter graphs show useful information by themselves, but allow user to see a bit more interactively. Should we make them blink once on load and show non-grayed-out unless the user mouse-over?