Using bow thruster to steer while underway

Are we sure that's not just someone making frozen blender drinks in the galley for the beautiful beach they're approaching?

You hate second guessing someone without having all the relevant info but sure looks to me like he's oversteering and making it harder than needs to be.

The only time I use my BT for steering is an occasional bump when trolling at slow speeds and if higher winds are pushing my bow off course. And by slow I mean on trolling valves doing 2 kts or less.

I frequently see owners use a technique that I call "drive by thrusters." They are usually rather new to boating and are probably the same ones that can't find their way from paper charts should they lose their electronics. When builders started putting stern thrusters as standard equipment, it encouraged the "easy" way to maneuver rather than the "proper" way. And if a yachtsman needs to use thrusters in open water, wait til you see them try to dock.

I have my favorites in the Nordhavn lines, but I hold a bit of a prejudice against the hulls that have been stretched. The N63 started as the N 55 then grew to 60 and ultimately a 63. No, the running gear was not stretched also.

Carl asked me to write a YF review on the 63 when hull #1 was cruising Florida. I had not been aboard the 63 and I had no knowledge of her, so I agreed and spent a lovely day onboard learning the boat. I have great respect for Nordhavn's success and was proud to write the review. However, I realized I was walking a fine line in upholding Carl's and my standards for honest reviews. If there are too many negatives, then we just don't write the review. And the N63 did not fall into that category as there were many good things to say about the 63, but if you read between the lines, you can find my criticisms.

https://www.yachtforums.com/review/nordhavn-yachts-63-expedition-trawler.18344/

Whew, long answer to your question, but hell no a trawler shouldn't roll like that and especially in those conditions as they appear in the video.

Something is wrong here.
Was he idling thru there?
Was it shallow and the bow was getting sucked down?
Stabilizers set to free? or just off? The following waves catching them?
Way to much stuff upstairs?

Yes, something is not right..
Too slow boat speed for normal steering..?
They lost control of the rudder?
Running on 1 engine on a twin engine boat?
(A bow thruster is an excellent back-up if you loose normal steering of the vessel, otherwise docking and emergency only)

Another observation;
Thruster running, wheel turned both directions.

One thing I learned long ago. Some APs can not do inlets on a following sea.
Was this guy baffled? No idea or clue? Was the AP running and just to slow over all to work correctly and this guy was adding to the issue?
What's with the rolls on a nice day??

Re-read post # 9
I really don't want to go hard against the guy in the video,, yet.
Any way to ask him Whisky Tango Foxtrot??

BTW
I've done better with one of two down coming in the StJohns with shift on my stern.
We don't need no stinking thruster....

Then he may had just be over cautions and running to slow,, way to slow?

I fully agree with all previous comments about the somewhat weird behaviour.
But I'm not so sure that it's just the helmsman to be blamed, because there are moments where the boat seems way too slow to respond to almost hard over steering, and that's the reason why he resorts to the b/t.
My guess is that he's going with a rather strong current, and if there's a mistake it's that he feared going too fast in terms of SOG, so he kept a too slow STW (say 2 or 3 kts), hence drastically reducing the rudder responsiveness. So, maybe with a more "normal" STW the thruster would have been unnecessary, but as I said I'm just guessing.

Ref. the stabilizers, I would think that they were not running at all in that video, for some reason.
Though a very slow STW would explain also a much lower fin stabs effectiveness.
Anyway, here's another video of the same guy, running in open sea and worse conditions, that shows how the same boat behaves with stabs running normally.
She's still pitching a lot, definitely more than in the OP video, but as we all know there's nothing stabilizers can do for pitching.
OTOH, rolling is pretty close to none, as it should be.

Next thing you'll tell us that you'd rather cross an ocean with a Sunseeker than with a Nordhavn...?

Only time bow thruster has been used was in new river. Couple of manatees traveling with us against the current. They weren't making much headway, were blocking the channel, making steerage difficult for us in a 73 ft trawler. Couple quick burps from the thruster and they moved to the side rapido!!