Why are NBC.com's "The Office" episodes longer?

Whenever I watch the full episodes of "The Office" on NBC.com, they are about 42 minutes long. I know that an episode on TV is only half an hour, and that's with commercials. Do they add deleted scenes?Why are NBC.com's "The Office" episodes longer?
The first few episodes of this year were 1 hour long. This weeks is the first of this season that was a half hour. They did some hour long and some 1/2 hour long the last few seasons.Why are NBC.com's "The Office" episodes longer?
No, the first 4 episodes of the season were hour longs. Now this week they are back to the normal 1/2 hr format. I'm not sure why they did all the one hours in a row. They do post deleted scenes on nbc.com, normally all of them have been posted by the next Thursday. So 'Local Ad' should be on nbc.com as a half hour.Why are NBC.com's "The Office" episodes longer?
No, first couple episodes were longer, last night went back to the regular 30 min slot.....