Yeah, the audio quality of the Countdown Japan video is garbage. Considering the time that was posted there might be a newer one out, or it might be the newer one. If it's the former, there's a better one, if it's the latter, then there's a worse one. In either case, neither of them sound very good.
The band I really can't tell out from the video I saw, it was all very muddy and kind of sounded out of focus, whatever the audio version of that saying is? Thankfully the vocals were captured better, but they're still off somewhat. From what I can actually hear, the girls sound fantastic though, and they looked like they were putting in a lot of effort and having a lot of fun, which is always nice to see.
As for that old interview, that really is OLD. They look so young there too. I don't generally watch Kalafina interviews on account of not being able to understand Japanese, although I occasionally have them playing in another window or something just in case they do something adorable (which happens quite often, honestly) because I like cute things.