Very big question, but an exciting space for sure. I am a big believer in this model, as the barrier to entry for creating specific, high-quality video content is higher than most people think.
I am happy to run you through all the steps in more detail, but it would take this trajectory if I were undertaking this project:
1) Deep Competitive Analysis on the niche you're planning to go after. What video content is currently being served in this market and how good is it? For example, categories like fitness, yoga and web/software development are not areas I would recommend going into for an online video instruction platform — they are saturated as hell. Let's choose something high-growth and relatively new as an example: podcasting.
2) In-Depth Writing on an Ultimate Guide to podcasting. Get this written yourself FIRST and then share it with a podcaster worth their salt for feedback, and even pay them to have them fix up what might be a 10,000 word guide on everything you need to know to setup a successful podcasting channel.
3) Once they say the guide is perfect, divide the guide in 20 chapters (500 words) each. These will be more or less, your templates for your initial 20 video scripts that will form the taxonomy of your initial video content library.
4) Find a video production company that has ideas on how to produce the video content in a way that uses mixed media: some live-action with a presenter speaking, some animated scenes with text, and some found footage or product screens. This approach will cost far less than a high-quality presenter to camera, and you will not get stung on things like continuity etc. Get them to produce 3 before you commit to the company for the whole set.
More or less, you're going to need to build your website alongside all these steps I've mentioned above. TL:DR — it is a bloody time consuming model, and I wouldn't attempt it as a solo founder unless you were doing it full time and had high trust with the video production company you were partnering with.
It is so very worth it if you can get it right, and there are tools like Uscreen you can use which will get you off the ground quicker.
Whilst my production company is probably not the best fit for this project, you could find some inspiration from companies we've worked with: https://www.vidico.com
Happy to talk over the rest in call — this is about 10% of what you need to do.