There's a lot of edge cases where you can get away with it but it's a bad habit to get into.

That said, the people who complain that literally every bit of content with a power tool doesn't start with the introductory lecture about safety need to go stick their hand in a wood chipper. That's like asking for every math class to start by reiterating basic arithmetic. It's an unnecessary drag on everyone for nothing. The people who need to be told to wear safety glasses aren't watching a youtube video on how to build a race car cage, they're not at that level, and the people who are watching it don't need to be told.