So speakers should blow when not turned on at all, right?
Obviously they don't blow when turned off, and don't blow when played at low volumes ever. So it's not a matter of blowing due to too little power.
Speakers blow for two reasons.
1) Their mechnical limits are exceeded, and something breaks (this seems rare)
2) You exceed their thermal limits, and something melts
You could for example, easily damage a tweeter by feeding it a continuous square wave or something IF you exceed it's thermal limits. Which is maybe not hard, as they don't handle a lot of power. It would have to be above the crossover so the poor tweeter has to dissapate the full power.
Speakers do have a continuos power handling spec. They can handle that in theory, but it's maybe based on music power and not some abusive signal.
What you might be thinking of, is blowing a speaker by (a) playing it too loud, while (b) running out of power in your amp which is powerful enough to damage the speakers. If you amp only had a half watt of power, it's not going to matter that it's clipping. So you need enough power, and oftenthe damage is because of clipping as that raises the average power that the speaker drivers are exposed too. Google 'why do speakers blow' (And note that there's varying explanations, some of which are probably wrong - here's one guy, an engineer, who is likely correct - http://sound.westhost.com/tweeters.htm
I did not watch the video, by the way. I thought it was better to just explain the facts of speaker damage (as I understand them