Repo: GitHub - angusmcleod/discourse-welcome-page
This theme lets you set a background image and a welcome youtube video for the login / signup page on a private Discourse.
@Martin_Cole a new member of our meta community, sponsored the development of this theme for Learning to Trade forum.
The theme has 5 settings.
It uses the same “lazy loading” that Discourse uses to load youtube videos in posts.
Here’s an example:
Hi this might be a silly question, but is it possible from a technical standpoint for this same functionality to be achieved in a Theme-Component as opposed to a Theme? Asking because the welcome page customization is a great feature, but as it stands it can’t be used in conjunction with a different Theme?
For more specificity, I’m running a private forum with the Minima Theme, but I’d also like to customize the Welcome Page using this functionality.
Edit:
Alright, I realized that the Welcome Theme could be combined with the styling in Minima so I forked and moved the files from Welcome Theme into it.
If anyone else needs Minima Theme + Customizable Welcome Page:
https://github.com/and-computers/minima-private-welcome-page
Not a silly question at all! Themes and theme components are very similar overall, and you can even convert a theme to a theme component with this convert button on the theme’s admin page.
So instead of forking, you can convert Welcome Page to a theme component and add it to Minima. That way you can still track Welcome Page updates.
@angus I’ve made a PR to change this to a component by default
Merged!
@weallwegot You can use this as a theme component now 
This Official Theme Component seems to be a good replacement for similar functionality:
