That's a great video, great for a quick and dirty api, a great starting point for your first api. I used to use the out of the box cf api, but needed more access to the request processing, router internals etc. Then moved to taffy, then wanted more, so now wrote our own lightweight layer, that runs api and web app from single codebase.
there's lots missing from a production implementation there, no security, no validation, formatting tools, versioning. You get all of that with api manager if you pay for ACF enterprise.
as 'overhead of a framework'
our framework (teamcfml) takes 120ms to load (with 10 services, 4 applications, 20 modules and 10 providers and 20 utility modules (formatters, etc) loaded.)