Yes, the "keywords" part is as important - if not more - in order for youtube to process the metadata for your content so it can match it with other videos and show them as related.
Without this it's virtually impossible to grow without people having a direct link to your videos.
The title should be short and descriptive and together with a proper thumbnail that you've made for each video things should fly! Look at popular videos for inspiration.
I've professionally worked with search engine optimisations and I know how to (ab)use the system to put someones URL in the top 10 results in Google search and since YouTube is owned by Google they are using more or less the exact same algorithm.
In metadata section list everything related to your content - even vague stuff, because it'll help you draw in the viewers.
Things like scale, modelling, model, build, armour, airplane, plane, Tamiya, airbrush, 1/35, 1/32, 1/72 etc etc is something you keep in a text file and copy & paste whenever you upload a new video so you don't have to redo the wheel every time

Too many keywords isn't good either but between 10-15 well defined keywords will help you when people search for videos and for you to show up as related/recommended.
The long description in YouTube is also part of the search but not as important as the metadata/keywords.
Also remember that when changing the metadata it'll take up to two days before you see any effect and never less than one day because it's done in batches, i.e. you can't search for what you've just entered and thinking something's wrong when you don't get the results you expect.
Good luck and remember - there's no substitute for great content. Great content creators will always get lots of subscribers and views.
People like Andy's Hobby Headquarters spend virtually zero time on making it look better than it is, just plain video. He's a good talker and makes regular videos that people find interesting and that's the whole secret. If he started to use fancy graphics and weird camera angles with dolly movements people would stop watching them... That's a good example of how to make interesting videos where the information is all there is.
A small catchy intro is a nice feature, but not overly important initially if you ask me... Better spend the time telling whatever you want to share!