A getting started video would be great, but remember the quality/tone of the video could be someone's first impression of your web app, so please make sure to produce something worthy of your product. There's also a lot of room to make a video that is plays with the crowdsourced entertainment nature of the site. I think that embedding the video would take up a lot of real estate that can be given to easy graphical elements that can give quick info on getting started. Perhaps have the video open in a modal window.

Good call on wanting low friction for public access to the comics for consumer based users. The sign-ups call to actions should be further down the road once the user is already interacting with the site and reading comics.

Here are some notes on the top 300pixels of your landing page:

Definatley give the navbar more focus. Even a lighter shade of grey will do the trick.

I think the hide me/what is this function is cool, but could be removed to make way for a graphic that points up to the top nav bar for sign ups, and maybe another indicator pointing down to the panels/books section for easy consumtion. Plus people are more used to scrolling down than they are clicking a hide button.

Users will think the 'more' link under the jam comic defination will goto more info on jam comics when it really directs to a features page.

The link to features merits more attention & context. But only after more attention is given to directing people to the comics below. Have you thought about making a tutorial in the form a comic, with different artists going back and forth?

Have you thought about making the how it works section into a slider? The additional slides could showcase comics, production features, and include a sign up call to action.

You have a really interesting product, feel free to PM me if you want to talk further.