The thread asking about software to slow the tempo of music in Spotify inspired me to share this useful extension I use. It doesn’t work for Spotify and unfortunately only works on Safari, but if you use Safari I highly recommend it! It’s called Dynamo and it lets you slow down or speed up videos in increments of 0.1 instead of the usual 0.25. It also uses keyboard commands, so changing the speed of the video can be done on the fly.
I find it useful when playing along to a song on YouTube and needing to slow it down a lot and then gradually build up speed. Of course, YouTube can do this too but you have limited options with how slow it goes.
Finally the best feature is that you can skip video ads with one keystroke! Saves a ton of time, and unlike other ad-blocking extensions I believe this way the content creators still receive revenue from ads while you get to skip them.
It does cost $0.99 but I’ve found it to be worth the price.