The easiest way to find out if there are any changes is to ask immigration on Koh Samui.What happens in other provinces is basically irrelevant. Your bank book shows your 800k and also that the transfer was international.
There are new T&C at least a couple of times every year at Bangkok Bank. The last email (with an attached pdf) I received about it was just a few days ago. There can be minor changes and nothing really important. It doesn't mean a "policy shift". I've been with Bangkok Bank many years and I have received a shitload of new T&C. Don't forget that requirements do differ between branches and provinces. That has always been the case.
When you apply back home, you just need the required amount of money in your local bank back home.When extending your stay in Thailand, you need the money in a Thai bank account. That's the difference.
Don't read crap like that. It's just scaremongering. Watching video clips on YouTube isn't imo the smartest move if you need correct info about anything.