Bad Wife? or Just Lazy? You decide...
So I thought...was there enough time to come to her sweet husbands defence??? With that...lets take a look at some quick numbers.
Now I'm working off a short piece of video so obviously I have to guesstimate a few variables. I'm guessing he's an average height of 6' and if he was stretched out and his head in the way of the lawn mower he would still be about 2' away from the steak in the middle. I'm also guess the speed of the lawn mower to be about average which is 3 mph. With that here we go:

First lets figure out the circumference of the circle. 8' radius (6' husband + 2' shy of steak) = 16' diameter x 3.14 (Pi) = 50.24'
Second, the time it would take the lawn mower to complete one rotation. There are 5200 feet in a mile and 3600 seconds in a hour so we take 5200 / 3600 = 1.4666667 feet per second x 3 mph = 4.4 feet per second / 50.24' = 11.418 seconds
So as the "husband" falls off, it would take 11.418 seconds for the lawn mower to travel around the circle and finally run over his head. Now we see that this lady is obviously in a side room which has a door to what one would assume is the kitchen. I believe it to be a kitchen because there is a patio in the one shot and I'm assuming the kitchen has a patio door leading to the patio.

Now there is no freaking way this lady can't run from that room, through the kitchen and to her "husband's" aid before 11.418 seconds are up. I submit to you that this is a bad wife, probably looking for some insurance money. Agreed?
Yes I do realize I have too much free time on my hands...you can watch the whole commercial below :)