Considering the state of the gun afterwards, it's a miracle he walked away. The really sobering thing about this particular kaboom is that it happened to a guy with a perfect 30 year record as a reloader. I think the message is that at some point, we're all gonna make mistakes, so do whatever you have to do to be as safe as possible, and hope you can walk away from your mistake.
we reloaders due need to have safe practices ingrained in to our head and never take a chance your life depends on it!
#1 I like to have only one powder on the bench at a time.
#2 then be for I load a single round I check scales
#3 powder for correct type
#4 check for the amount I want to load
#5 then check powder thrower for correct weight
#6 then start at #2 again.
Getting back to the topic, ahem... I use an electronic scale. But the last electronic scale I had went bad, and started shifting zero while I was using it. The worst thing about them is that they work perfectly until they don't.
The "one powder on the bench" rule becomes more important the longer you reload, because you start to accumulate different types of powder.