I would love to see this for mine and other creators comics! The biggest type of advice i can give you is to make sure when you review peoples comics you be as consistent in your critiques as possible. redrafting your own script as you critique is important! ^^ If you do pursue this I wish you luck!
I also don't think you need to ask for permission persay so long as your making sure its clear who the creators are (leaving links to the comics or stating the creators names clearly in your titles) maybe let them be aware that you've made a video of their work, but so long as you're following the guidelines of fair use theres noting wrong with reviewing someones work with or without permission as its in the public eye.