I don't know what you have running on your Macbook, but I have two Macbooks, one new and one about 2 years old, and my kids watch hours of Flash videos and Flash games until I have to wrestle the computer out of their hands because it is bedtime.
This "30 minute battery life" smells fishy. It is a friend of friend of a friend who woke up one day in his hotel room with his kidney removed and his iPhone battery drained.
and watched the resource use. While the video was playing, the minimum CPU use from Safari was 48%, with frequent spikes above 60%. As soon as I closed the tab, CPU use dropped to about 2% and stayed there. On a laptop with a full charge and power-management profiles to optimize usage you can get away with this; on a power-constrained mobile device you most certainly can't.
This "30 minute battery life" smells fishy. It is a friend of friend of a friend who woke up one day in his hotel room with his kidney removed and his iPhone battery drained.