I love RJ the Bike Guy, he's my go to Youtuber for bike maintenance.
I'm glad to see he's started posting again. I really should download all his videos and keep them in a folder on Google Drive in case he ever disappears from Youtube
But I have to say, this particular video is a case of 'Can it be done?' Rather than 'Does it need to be done?' considering the price of bottom brackets.
But of course your bottom bracket may have the exact lengths either side that you need that you can't find elsewhere, so it's all good.
The sellers of bottom brackets never state the lengths of the exposed spindle on each side, they only ever state the overall length of the spindle.