Agree with your opinion. This is also my understanding, please correct me if you think I'm wrong. When he said loss with DCA when the market goes up, you don't really lose, you just gain less than investing all at once. Likewise when the market goes down, you lose less than investing all at once. So, overall, DCA serves as a safety net to minimize losses, while limiting profits. The DCA method is more like value investing...
In this case, the price at which you start DCA is very important. And if you decide to start accumulating Bitcoins at the current price using the DCA method, then you will not need to be surprised that the price may decrease and your investment will have a negative balance.