Syntax is left bracket "[" followed by "spoiler" followed by right bracket "]"
Then what you don't want people to see unless they click on it
Followed by left bracket "[", backslash "/", "spoiler", right bracket "]"
Quotes are not used here, I used them to indicate what is required.
Should work like this:
Spoilerwhat you don't want people to see unless they click on it
You're welcome. There's a tip jar on the way out, thanks!
The reason the above looks more complicated than it is, is when I typed it out, VB4 tried to do it instead of allowing me to show how to do it, so as a result the instructions were borked.
A simpler way for me to say it would have been: if you can post videos from youtube here, replace the word youtube with the word spoiler and put your hidden text in the middle of the brackets. Done.