No - it's free to use. You need a YouTube channel, laptop / smartphone to stream from, then you're good to go.
To broadcast from a mobile, you'll need to have at least 1,000 subscribers, but you can stream from a webcam (i.e. your laptop) without restrictions. You might also have to wait a little while (24 hours) when you first try to broadcast for your account to be verified by YouTube, so it's worth getting ready well ahead of time.
Like with Facebook Live, participants just need to have your YouTube channel up when you start your public live stream (or access the specific link you've sent them if you've set up a private live stream for your class).
We've all seen YouTube videos, so you can imagine how it looks from the participant's point of view! 😃
Apart from comments, this is a non-interactive option - you cannot see the attendees, only they can see you, so it's good for mass audiences where you're not looking to give direct feedback or motivation to individual participants.
It's very simple.
Log in to YouTube (or create an account). Click the video camera icon (in the top right if you're on a laptop or the YouTube app), and in the drop down menu select Go Live.
Go through the account verification steps if you need to - this may take up to 24 hours to come through.
On the next page, you can add details about the class you're going to stream, including the Visibility settings - public (anyone can find and watch), unlisted (only those with the link will be able to find and watch) and private (you can select specific people, via email address, to access the video - up to a limit of 50 people).
You can also select a time to stream the class, which is a good way to get everything set up (generate the URL, etc.) ahead of time, so you can communicate this to participants.
Send the YouTube link out to your participants, either ahead of time for a public URL or send the unlisted URL just before the class if you only want those who have booked / registered to be able to watch your class.
YouTube is very strict with copyright regulations, so be careful if you're using any music during the class. YouTube has its own library of audio content you can use if you're not sure.