Feature request: add option for different playback speeds

[niklasberlin]

it would be great to have the option to increase or decrease the playback speed of the video like in the official Mediathek. With the used video-js player this should be quite easy as far as I understood the documentation the video-js project offers this functionality out of the box. To enable it, the

in short: add the following attribute to the video element to enable different playback-speeds: data-setup='{ "playbackRates": [0.5, 1, 1.25, 1.5, 2] }'

relevant topic in the video-js Documentation: https://docs.videojs.com/tutorial-options.html#playbackrates