USe the tags [] and have yt in between them, and than put the youtube code
youtube.com/watch?v=sIVFW91CIvM
After it, and than finish it off by putting the two [] and than / yt in between them.
Also make sure that you ONLY put the code and nothing else, the code begins after the equal, and it ends before the and symbol, and an easier way is by clicking more on the side were the video information is, and than use the code in the link.
Inshallah this'll help.
Assalamu Alykum.