You're definitely going to have to spend money on materials and there's really no way around that until your work is able to pay for itself. There's no reason why you can't do it, as long as you're ready for the dedication required to create a comic and your work is up to par.
Don't think about doing it, just do it. Don't wait till you're 'better' because you'll always be playing catch up with your own skills. Don't wait till you have a story 'idea', go out and find it.
Just do it.
Write short 2 or 3 page stories, not just a big massive long one. Do a short comic of two people talking. Do a comic set on a bus on a train in a fantasy castle, it doesn't matter. You don't even have to go to the huge lengths of "publishing" it like a long series webcomic, just have fun, maybe post it to dA, or start a webcomic if you like.
Drawing a comic, (whether that be manga style or otherwise) uses skills you'll never actually learn any other way than by doing narrative illustration. Why try to improve first, improve while doing it!
Perhaps if you've never done sequential work before you should have some fun with some short scenes, instead of a full story. I dunno your characters are at dinner, or joking about or whatever you want.
You could start it now if you wanted to If this is something you'd like to create just for the sake of having fun, then there really should be nothing stopping you. And working on a project like this will give you motivation to keep going and try new things, which in turn will help you improve your work greatly, and it'll be awesome looking at the beginning of the story and compare it to the end. Why don't you try working on something small first, like a 5-10 page comic, to get your feet wet and see how you like the overall process?
Sure. Manga's easy. If you can draw, say, about 1800 rectangles, stuff some people into them and put in some words you have yourself an online manga book. It's long and tedious, of course, because 1800 panels take a while to draw and most people get bored after about 60, but it doesn't exactly require superhuman genius. Just a lot of patience and stick-to-itiveness. Thousands of people are doing this even as we converse.
OFCOURSE its possible. You write it and you draw it and you show it to people.
Not sure why you would put a comic on youtube however. Seems very awkward to compose a slideshow video in a separate piece of editing software rather than just putting it up somewhere and let the reader enjoy it at their own pace.