Laying out your wool with the most successful primitive wet felting techniques 

It does not matter what kind of soap you use, but she is clearly using Dawn dish soap, and she recommended bio-degradable soap. Almost all soap is biodegradable, unless you go out of your way to use something harsh like detergent. A lot of felters recommend Palm Olive dish soap, since it's gentle on your hands, but you can even use baby shampoo or bar soap. Again, it doesn't matter, just use what you have.

@@abbybose7671 Helpful comment, thank you!