There are certainly many cases where using video instead of GIF makes much more sense. But if you're talking about continuous animation of 10+ elements, then I'm not sure video is a good idea.
We recently optimized electricitymap.org to use GIFs instead of CSS/SVG animations, reducing CPU usage between 50-95 percentage points (depending on setup). In our case, we were animating ~70 arrows causing 100% CPU on many machines, including my own beefed up MBPr from late 2013.
Looks great indeed, there is also the option to dynamically render the SVG animation to a sprited or multiple canvas once, and avoid to reevaluate and render the SVG for all instances on every frame.
