This keep-it-simple plugin is useful when you want to pipe arbitrary
data to a different pipeline within the same process. Some advantages
over appsink/appsrc, the inter elements, etc:

* Ease of use. Buffers, events, and caps are transmitted as-is without
  copying or serialization.
* Enables zerocopy (especially DMABUF) transparently without any
  special-casing.
* Enables usage with sinks or elements that are unreliable and may
  throw errors and need re-initialization, such as a network sink, a
  USB device sink (v4l2), etc.
* Transmits arbitrary data, not just audio/video/subs
* Can easily implement 1 producer pipeline -> N dynamic consumer
  pipelines within a single process when combined with the `tee`
  element.

All queries, events, buffers, and buffer lists are proxied. State
changes, clocks, and base times for the two pipelines are independent
since the upstream and downstreams continue to be different pipelines.

https://bugzilla.gnome.org/show_bug.cgi?id=788200