After watching the clip about 5 times in a row, I disagree with this statement. 1675's only goal at that point was to get on the other side of the defender and get to the scoring rack. During the two-robot spinning motion, 1675 was on the opposite side and there was really nothing to stop them from translating away from 2761, as shown below -
I think what contributed to this motion was the mecanum wheel rollers being pushed from the side by 2761. The real trick would have been timing the translation correctly.
There's a lot of strong opinions about mecanum drive systems here - which is fine, everyone is entitled to their own opinion. The way I see it now with AndyMark selling mecanum wheels is that this gives teams an opportunity to have an omni-directional drive train with very minimal effort. So you have every team under the sun buying a set and trying them out, even if they aren't necessarily implemented correctly. More often than not, I see teams driving tank style with two sticks, completely ignoring the mecanum's translation capabilities.
So what does this come down to? Mecanum drives are inherently more difficult to control than a standard tank style drive. You can show someone immediately how to operate a tank style drive train and they'll understand it. They won't master it immediately, but I would argue that the amount of time that it takes to 'master' a tank style drive train is less than the time it takes to 'master' a mecanum drive train. No hard evidence to back up that claim either, just something that I've observed.
Most teams don't build second robots and don't have much driver practice time. So when they choose a mecanum drive, they are probably still trying to figure out how to control it out on the field. I think this adds to the perception that mecanum drive systems are a bad choice, when in reality the learning curve is just larger.
I agree that there are inherent disadvantages to using a mecanum drive, and that if your team has the time and resources to build a swerve drive system, then that is the way to go probably. But most teams don't. So they sacrifice some pushing power at the cost of omni-directional maneuverability.
One of our goals this summer has been to get students driving mecanum every week. We will see if it pays off next season - who knows, maybe we will finally be able to produce this fabled mecanum vs. six wheel video.