It takes time to get up to speed on work. So to really be productive, you need that time to get up to that speed, and not be interrupted. But after time energy lags, and productivity drops. The video is compelling in this regard.
Then it suggests switching gears and working collaboratively, but that point was weakly made.
http://www.youtube.com/watch?v=4qRsyp0B4CM
The pomodoro technique and the Results Curve :
http://www.productivityhacks.com/time-management/workflow-steps-pomodoro-technique-and-the-results-curve/