You also have 4 yellows (funny enough Dawa is actually good under this context). You could max out another yellow for a mono yellow. The only one I see on your roster is Kailani, which has low tile dmg but at least is a yellow (and you can use her on 3* tournaments where purple is denied), so she wont be a completly useless investment (even if in the long run you may switch her off for 3* Events).
For your red mono, max out your Rudolf follow by Azar and Nasghgar. They are your 3 reds with higher tile dmg.
Hawkmoon with a custom would be a nice and not to hard addition.
But from now on, you will want to keep Namahage, Rudolfs, Squires wabbits, Gatos even Customed Banes are an options nowadays.
And stuck as many as Axes, Arrows, minor and mana potions as you can.
Last but not least, and probably the best advice you can get around:
The video is old and it was made in a time before the Event revamp. But I would say that a lot of what is beeing talked stills hold true to today.