Actually they fixed the perf, which was the main complaint from those videos.
"These internal Microsoft videos, provided to Wired by a person who worked on the project, show focus groups testing the ill-fated Kin. According to our source, these are pre-production models that changed very little from the shipping product, although “performance improved some prior to shipping.” Watch them, and you can readily see why the project tanked: Kin phones just weren’t usable."
This is obviously not true by just watching the videos. In the videos the delay between typing a number on the keypad and it coming up is something like 5 seconds. Watch any hands-on video after it launched and you can see no performance issues like that. Kin reviews noted some performance issues, but nothing to the degree noted by these videos.
performance improved some prior to shipping
I think that would be an understatement given how poor the perf in these videos were. It would be like doing a test group on the iPhone where dragging and tapping was delayed by a few seconds. There's no reason to even test that, because it will break everything else in the UI.