Unfortunately it looks like we cannot reliably capture from c-span.org at the moment. We will add support for this site in a future update if we can. Sorry about that.
In particular, it looks like they have several services they stream from and we can capture from some but not others, which is why it seems random.
Using Jaksta on Mac, behavior on C-SPAN.com is somewhat erratic. Often, though not always, the short C-SPAN intro clip is recorded but not the following video that I am actually trying to record. Sometimes Jacksta manages to get both, sometimes it discards the Promo and then does not record the actual video, occasionally it discards the Promo but then successfully captures the actual video. Occasionally it functions in chrome but not in safari. Sometimes in safari but not in chrome, often in neither. occasionally changing the minimum duration helps but not always