I have been doing a bit of YouTubing - checking people out who are also doing the 100 Burpee Challenge. It appears that some are doing burpees differently. I adhere to the rules on this page.
What I am mostly seeing in videos are people who are combining the action of kicking the legs out and the down portion of the pushup. In other words it looks sort of like a sprawl. In my burpees I tend to separate the actions.
2. kick legs out
3. do a good pushup with good form
4. legs in
What I see a lot of people do is this.
1. jump up
2. come down with legs out and in "down" pushup position
3. push up and jump up
Here is an example:
I am not saying the person in the video above isn't doing a good job at getting exercise, I am saying that I don't think that he is getting the full value of a good burpee, especially the pushup part - and us guys want nice big solid shoulders, arms and pecs.
The FIRST people in the video below are doing them the way I am, separating the movements somewhat. Note the woman drops her knees, as my wife is in her modification since she doesn't have the upper body strength to do standard pushups.
My .02 on burpees.