Adjustable playback speed for videos and scripts.

The Handy Playground Alternative Video Player (https://playground.handyfeeling.com/localplayer/) has the abilty to quickly adjust the speed of the loaded video and script (Or just script, if no video file is present).

Sometimes scripts are way too fast (or too slow!), and being able to move a slider down to 0.5x speed on the fly is incredible and is the main reason I use the Playground player. No other player I've found has this feature, and I was sad to find the Playground player had recently broke with the API changes. As such, it would be great if it could be implemented into the main website's player.