Just curious how long you are locked in to the publisher you mentioned in the video? Self publishing is the future, and would allow you total control over promotions and such. Hated seeing you are locked in for a minimum 90 days at Amazon through the KU program. Go wide (Nook, Kobo, Apple. GooglePlay, Smashwords, etc) as soon as you are able.
https://www.smashwords.com/about/how_to_publish_on_smashwords
Promotion sites:
https://www.freebooksy.com/ for free promotions
https://www.bargainbooksy.com/for-authors/ Same company as freebooksy, but for discounted sales.
Those two are your best shot coming out of the gate.
Most of the others aren't worth your money. Bookbub is the holy grail, but no way you can get one being exclusive with Amazon.
Smashwords allows the most control, with coupons and such, plus acts as an aggregate (as does Draft2Digital).
Twitter blasts do not work via the tweet companies. You may try an alternative marketing method (I couldn't as I didn't write this type when I was self publishing) and see if you can make arrangements with popular YouTube channels to give you shout outs.
Good luck, and don't get discouraged if things are slow. Many self pubbed authors lose money, and your best advertisement is the next book.
Writers forum
https://www.kboards.com/index.php?board=60.0 They lean left, but there are some successful self pubbed authors there. You can pick up some good ideas there.
RE: How to get your E-Book published, what steps will make it faster and easier - How an author can work their novel into the Steemit community