The problem with a lot of environmentalism is that it represents otherwise minor issues in an overtly dramatic way. The core message of this video is entirely correct. It depends on what you mean by "soon", in a world of short attention spans and instant gratification culture, the fact that we're still alive 19 years later may seem to invalidate the suggestion, but 19 years are absolutely nothing on an evolutionary timescale. And while we are setting ourselves up irreversibly for extinction right now, unless there is an all out nuclear war, most likely there will be people alive hundred years from now, maybe even thousand years from now, and maybe even longer than that. The question is what state the planet will be in, what state humans will be in as a result and how this will impact our survival chances in the really long term. That's very really discussed in the serious way it should be discussed (even though it should actually dominate the public discourse) and I can easily see why people may be put off by messages like the one in the video above.