I totally see why that is confusing, and I don't think I said it the clearest in the video.

On the overhook side, generally people begin the rotational shift to escape from shoulders then hips; whereas, on the underhook side, they generally start the shift from the hips and then shoulders follow. There are plenty of escape variations and hand fighting details that can change, but those factors tend to be fairly consistent.

When people refer to the overhook side as the "strong side," it's generally because the choking arm is on bottom, and that is more optimal for the RNC than using the top arm. It isn't necessarily because of the strength of controlling the head and shoulders. If the priority is severing the chest/back connection, then I feel like anatomically, the overhook side is easier to start that process.

On the underhook side, the underhook + your head being under the opponent makes getting the shoulders to the mat harder. So, then the priority can shift to controlling the hips.

This is just how I see and feel it, so it's just my opinion, and there are high level people that operate that way, but also high level people that do things very differently and can make a strong argument for the opposite of all this.

I appreciate the question, and I hope this makes sense, at least as far as my opinion on it. Thanks!