Oh man, that's the worst. It's hard enough doing the job without someone breathing down your neck second-guessing every move. People really forget that watching a video doesn't teach you the feel and flow of actually doing the work.

@stone.evan nailed it, Google hates the old robot tricks.

My buddy Mark called me last week from a job in Tucson, told me he tried that same thing with a utility knife on a full strip of corner bead. He said the bead bent weird and left a gap that took him two hours to mud over. Then @the_seth chimed in on his post saying the heat makes the metal too soft for that method, which I guess makes sense. Mark ended up ripping the whole thing out and starting over with precut pieces. He's back to measuring twice now.

Oh man, that brings back a memory. I tried the same trick on an old farm gate latch last winter that had been frozen solid for weeks. Ended up having to use a propane torch anyway because the WD-40 just wasn't cutting it in that cold. But hey, at least the bolts on my truck's trailer hitch came loose no problem after that.

Learned that one the hard way myself. Guessing is embarrassing.