Where did the 1 in 10 stat come from? I only skimmed the video.

Anyway, there is suicidal ideation, and then there are suicide plans. Ideation is "step 1", the thought of killing oneself, which is certainly not harmless and often a sign of larger psychiatric issues. However, a suicide plan is "step 2" in the process, and requires intervention. I doubt that 10% of teenagers have a real suicide plan, although I wouldn't doubt that many teenagers have occasional thoughts about it.