The main thing is try to play perfectly or terribly. Average is pretty boring, but the limits on each end are pretty funny or educational, depending.
(@DJ - my post isn't a reply to you specifically, but this sparked a train of thought so I'm including it)
I think you have to have a big personality to play terribly and hold an audience. I had to stop watching Day9 because of his play. I can see why he maintains a large audience tho, because of his gregarious and fun personality - but it reached a point with me where it was just too frustrating to watch him play. On the flip side, I enjoy Semioni even tho he's more dry, because he plays pretty well, he sees his misplays pretty quickly and points them out (which helps you learn and demonstrates he knows how to play well). I don't think you have to be amazeballs and perfect, but you'll need to be better than average if you don't have the personality to carry you. To attract audiences you'll need to be fun (someone like Day9), educational (someone like LVD), and bonus if you can do both (someone like Noxious).
You'll probably want to find a niche to sit in. Not be restricted to it exclusively, but have something that people know you for. Semiomni produces a large volume of limited videos, CGB has his series on FTP and helping new players, LVD has his weekly calendar of different video types, etc. During Duels, I got into Nighthawk and SLM because of their spicey decks (and Nighthawk has his trademark 61 card lists). Think it really helps to have something you're known for.
Partly for selfish reasons (because I've been really into these types of video the last few sets), but also for practical advice, limited format content seems like a good place to find a niche as an unknown. It's not as saturated as constructed. Easy to get lost in the sea of constructed content (millions of spike, theme, and meme decks) - but limited is a smaller pond with fewer fish to compete with. When I do YouTube searches for sealed or draft videos, it's easier to see small channels on the first page of results.
Lastly, I think unless your channel is huge and you simply can't keep up with the volume of comments, its important to engage with your audience. Replying to people's comments helps keep them engaged and become invested in you.
My 2 cents anyways.