I don't have a suitable definition for Bitcoin or alt-coin, although I'm happy to make observations on what other people think.
IMO it would be useful to distinguish blockchain forks that happen intentionally to make an alternative system, and maybe that's deserving of a new word other than altcoin, particularly when it's an attempt at an usurpation as it happened with Feathercoin or what BitcoinXT would aim to achieve.
Maybe altfork? However nobody says that.
Frankly I think altcoin is a neutral term and sometimes, albeit not often, they are perfectly legitimate and worthy of praise (as opposed to the XT hackjob).
The other question is whether something can be simultaneously "Bitcoin" and "an altcoin" given this definition of altcoin in the wiki, and whether XT is that.
Watch the entire interview and you will see clearly what he is saying in context, he was discussing a worse case scenario where there is a split between east and west. His actions speak louder then his words, just look at the code. Bitcoin XT will only fork if a seventy five percent consensus is reached, saying anything contrary to this and talking about checkpoints and ignoring the longest chain in regards to Bitcoin XT is really just pure FUD.
https://www.youtube.com/watch?v=8JmvkyQyD8wLearn English.
Worst case as in it didn't happen the way he wanted, so why not going ahead? because he's a coward and he knows he would absolutely fail to get all that support he was so sure to get.
I watched the whole thing long ago. He turns my stomach, the little cunt. Even more now after seeing he doesn't even keep his word.