I haven't added Khan Academy yet. However, that should change soon...

Interesting. I will definitely consider adding filters in the future.

Originally, I just wanted to a build minimalist search engine that just gave the bare essentials (kind of like Google?)

I like the minimalism. Filtering is great, but more valuable when you know exactly what you want. That said, a (very) few filters for the most common reasons a searcher knows that they require would probably be helpful. Maybe start with just a free/paid filter?

Another filter: language. Many people don't speak English. Maybe you can automatically detect the language and add to your list of languages as you go?

Another filter I think is very important: only courses that have video lectures.

Haha, yeah. I'm still working out my Elasticsearch queries. I thought it was working well enough to at least get some feedback though.

Flask for web framework, Elasticsearch for search. The speed might be due to the fact that there is no JS / images on the front end.

Just had a conversation last night about SQLAlchemy support of NoSQL dialects like. I bet you didn't use a Model layer. Right? Is there anything you want to share in that regards?