@odd I'm guessing that designs like that would probably run into performance issues on many devices in browsers today but haven't tested directly. Probably would depend very much on the device and the specific SVG.
In theory, this should help with that, though, once it lands as it would enable hardware acceleration of both the video and SVG layers. Chrome has a similar project in the works and FireFox has been working towards greater hardware acceleration for a while, so, fingers crossed, the future of SVG animation is going to be a bright one 🙂