Documentary in HTML5

The documentary One Millionth Tower was made using animation in HTML5, as described in "Here’s How You Make a Documentary Only Using HTML5 and WebGL Graphics" (By Adrian Covert, GIZMODO, Nov 6, 2011 11:30 AM). Like many documentaries, this one relies on panning and zooming over still images. In theory, using HTML5 should make this more efficient as a still image can be downloaded, along with the instructions for how to pan and zoom it. But in this case the documentary is 163 Mbytes for 6.5 minutes, making it 25 Mbytes per minute, which is not small.