I don't think the main graphic SE would be the place to do that. For Graphic design and SE philosophy I think it would be a wonderful idea though. You would have to be able to embed youtube or vimeo video as well. voting tutorials up or down would be a great idea.
Tutorials are encouraged in GD.SE! By all means, you are more than welcome to post your own step-by-step guides as answers (there are some really good tutorial-answers in the site, some even include animated gifs).
My only concern would be the videos. Ideally, all answers should be valid by themselves. This means: You shouldn't need to leave the site to solve your issue. The problem with videos is that they are hosted somewhere else, so the answer becomes dependent on them. If the videos goes down, the answer becomes useless.
That's why we always prefer written answers. Having said that, if you have made a great tutorial that answers a question, you can post it! Just try to make sure your answer is still valid (video is still hosted) when time passes, and that the answer is removed if the video goes down.
Some examples of tutorial-answers: