Adjust the speed on the snail setting#40

I like the slow down feature on the listening videos using the snail setting, but I would like to be able to choose a percentage of how much to slow it down. For example, right now it slows to maybe 75% and it is too slow for my students. I would like to be able to choose 80% or 85% play back speed, and choose how slow the videos will play for the different levels I teach.