Embed Youtube with Captions on by default not working?

I'm trying to embed a Youtube movie, and would like Captions to be on by default. From https://developers.google.c...

Failed to execute 'postMessage' on 'DOMWindow': https://www.youtube.com !== http://localhost:9000?

This is the error message that I get: Failed to execute 'postMessage' on 'DOMWindow': The target origin provided ('...

YouTube: How to present embed video with sound muted?

I'm trying to embed a video with the sound muted but I can not figure out how it make it work. Currently I'm using ...

YouTube: How to present embed video with sound muted?

I'm trying to embed a video with the sound muted but I can not figure out how it make it work. Currently I'm using ...