I've backed almost 50 projects on Kickstarter -- in publishing, comics, video games, and the occasional tech item.
However, the other type of Kickstarter funder are people like me who look at pitches and think about whether the project or creator are worth the risk (e.g., the output is worth gambling upon).
But serial authors have an enormous sample to look at. They also are a lesser risk if the book being crafted is being developed from a completed piece. The time to delivery of the kickstarter goods should be theoretically less than most other categories.
You should have a strong case but your case isn't coming through.
vState the link at least once near the beginning and also at the end.
Lastly - you are very nervous! Write out a script for yourself or a good outline and practice it a few times in front of your family before recording. It's the same as preparing for a presentation, do it over and over until you sound natural. Or-- if you want to be cute, get more pictures/diagrams thrown in, go all text, or get your fans to help you with your video
I would drop what you mention from your video pitch. Anything that appears to finance a life-choice or anything that isn't necessary turns people off. Therefore I would not mention the computer. Writing on your iPad will not be perceived as a hardship.
The RPG -- Is it based on fan demand? Is it just a neat idea? I've been left with a vague impression that this wasn't researched. If it has been, tell us in the text e.g., "Many of my current readers have asked about a RPG version set in this universe. I talked to a reader who has five years of experience developing games and provided an estimate." That said -- Tabletop games are often kickstarted and I'm not sure about your figure. It kind of sounds too low -- do some checking on other pitches on KS. (See https://www.kickstarter.com/projects/1116606684/heros-journey-a-tabletop-rpg-of-myth-and-legend for an example.)
You also should consider that the tabletop game could be carved off into its own kickstarter and leave it at that. Come back for it another time. Many webcomics tried to throw this in as a stretch and they failed. It has nothing to do with the book.
Remind us we can read a sample (and provide that link in a prominent fashion) . This is your what makes you stand apart from other publishing pitches that sound like "help me write my first ever book and you have no idea if I'm good."
Look at these projects which were similar to yours in niche:
Similar issue with t-shirt. I think I need to understand what this t-shirt is and it should be described in the main-text. People obsess about t-shirts. They want to know design, colors, available sizes before they change to a higher tier pledge or go for that off the bat. This has been true for every webcomic/comic fundraiser I've supported as well as Planet Money's t-shirt campaign.
Consider a website acknowledgment as a part of a tier.