No. This video show almost nothing. But it is stille better than many other machines - I agree on that. Let me explain.
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This video shows jump start to a rather high speed of about 60 stitches per minute. The machine cannot make very low speed, and it is typical, that these servo motors got a limited speed range often about 1:25 or perhaps up to 1:45. Look at other video and compare and you see 8 stitches/min and no jump start. Jump start do also mean, that you cannot hear when the machine will start to sew. Suddenly it starts when you press the pedal sufficiently.
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A slow speed increase to max speed is not shown, and it will probably have some uneven behavior.
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Very small steps forward is not shown, and I know you cannot do that with the pedals they use.
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when it runs that high low speed, then it is hard to evaluate how it reacts to load variation. But I think it is reasonable.
The servo motor you show is for an industrial sewing machines, and they got very high torque in a set up like he show with reduced gearing. It is hard to limit the torque, and you can easily get a household vintage sewing machine damaged by that.
The man in the video is happy about the performance, because many other machines is a lot worse. And many users are used to worse situations. But it does not mean, that there is still room for a lot of improvement.