It all depends on how much time and determination you’ve got. If you have a full-time job, seven kids, three dogs, and are in the middle of moving house, forget it. If you are independently wealthy, have no family or friends, no hobbies, and have decided to devote your life to reading manga, it is perfectly possible to follow along and learn loads!
Regarding YouTube videos, I can’t really speak for Cure Dolly (I’m one of those people put off by the presentation I’m afraid), but can say Missa is totally excellent!
One problem you’ll have in the early stages is mustering your resources! There are so many out there that you won’t know which is best for you, until you try them all. And than in itself takes a lot of time. I have loads of resources bookmarked, but now only use a small handful of them. Take a look around the forums for ideas. I believe there is a thread devoted to resources, and the master list of study logs will give you loads of ideas based on how other people study.