Here is a very brief pearl knotting tutorial from Little Happy Apple, who writes a crafting blog. I love her description of herself on YouTube:
crafty adventures of a girl who still manages to make pretty things with three kids, a dog & an awful lot of dirt
As I mentioned it is a very brief tutorial, but I think very clear and helpful on the issue of knotting pearls, which people are always asking about and which can cost quite a lot to have done professionally. I like that she uses the bench to steady the tweezers, good idea! I have tried the more expensive pearl knotting kits that you can buy, but in the end I find that tweezers are the simplest and best tool for the job.