As discussed in this article:

Markplier’s plan? To not only get Iron Lung up for digital purchase on YouTube, but to also set up a new system within YouTube where other filmmakers can do the same with their films.

Markiplier explains in a new video, “The reason Iron Lung‘s digital release has been taking so long is because I’ve been taking the extra steps to work out this deal where I can become this aggregator so that other people can benefit from it. That’s the goal. And that’s what I’ve been trying to do. And there’s a lot of legal loopholes to do it, and there’s a lot of setup to do it.”

[…]
As for the physical media release of Iron Lung, that’s also in the works. He explains that he’s going to literally have a DVD/Blu-ray machine that will be auto-producing copies of Iron Lung in his home, allowing him to self distribute the film on physical media.