I've been watching BSG for the better part of 5 years now, and it's never failed to amaze me quite how good it is at so many things. Intense personal drama, big themes, a sense of intimate character and major action set-pieces are all things it's proven to be good at on the TV.
Also impressive was the TV movie Razor (I've yet to see The Plan, despite having it on blu-ray. I'm waiting until I've finished watching the full series through again). So BSG can do long-form and medium-form (short form, for the purposes of Hugo nominations). And, apparently, it can do very short-form as well.
The Resistance (originally titled Crossroads) is a series of 10 webisodes based around the formation of the resistance against the Cylon occupation of New Caprica, forming a bridge between seasons 2 and 3 of the main show. I've seen the main series without having watched the webisodes, and can honestly say that having not seen it doesn't detract from the story one bit. However, it is still worth watching.
It's more than a little jarring to watch the blu-ray release and find that the picture quality is still only that of a streamed video off the internet, especially after the full HD of the series itself. But the production values are high for what is a fairly obscure bit of Galactica canon and the acting is at its usual high standard, with Michael Hogan in particular putting in a strong performance as Colonel Tigh.
The Resistance goes some distance to explaining why Jammer was to be found lining up in the Cylon police ranks at the start of season 3. He is the central character of the webisodes, alongside another of BSG's lesser lights, Duck, the Viper pilot. As usual, the story is very focused on the human reactions of characters to their situation. Jammer experiences moral revulsion at guns and other armaments being hidden in a temple; Duck reacts badly to the death of his partner, Nora.
The webisodes throw some fresh light on the opening to season 3 in particular (up to and including the episode Collaborators) and are an interesting diversion fans should seek to get hold of and watch. Despite being short (the total series running time is less than 30 minutes), it's a worthy watch.