Nope! It's all running client-side, so it uses a bit more bandwidth, but there's no way a serverless platform can compete with the cost :)

If the tool is popular long term, we might do a serverless option to make it accessible to Safari users or something though.

I'd be curious what difference it makes. Supposedly fastly compiles wasm down to native first, so it should run faster. Obviously fetch time would be faster since it's sitting on their hard drives. Data transfer would obviously be video file size and bandwidth dependent. A lot of variables there, but still it would be interesting to see even for your particular bandwidth and distance from a fastly server, for what file size the break even point is (for a few different operations).