I just watched the first episode...I think
Would that be "Rise of the Old Masters"? It was first on the page at the URL you gave, but on the front page of the site there's a different order. The story felt early, but the lack of backstory told me I started late.
There's a double-length episode listed called "Spark of Rebellion" with a blurb about "a dark time. The Jedi are no more..", which sounds like the bridge between the first and second big story arcs. Is that the origin story I should have watched first?