[Invokers] no magic defaults please

[tomByrer]

<button invoketarget="my-video">Play/Pause</button>

I do not think there should be magic defaults like this. Could be mis-labeled & bad for ARIA, etc. I'll grab the attention of others in the Video Player field to chime in, but for now I'd like to see:

<button invoketarget="my-video" invokeaction="playpause">Play/Pause</button>

& then one can CSS:

button[invokeaction="playpause"] {
  background-color: gold;
}

Otherwise, great proposal!