can i use characters from movie clips on my youtube commercial? can i have an impersonator use film of different celebrities and voice over my commerc

The short answer is no, not without authorization from the owner of the rights in those characters. And many of the owners of popular characters are strong enforcers of their rights. Same with celebrities - you cannot use their likeness, image, voice, either directly or through an impersonator where it is clear who is being impersonated, to offer commercial goods/services without their permission. The laws on the celebrity "right of publicity" varies from state to state, but if you are going to be on YouTube, you will have to comply with all of those laws and not just your state's laws.