My main complaint about this episode is that nothing happened with the inventions. There were no more tests and no more modifications.
True we got to see the finalists going through the difficulties of making a commercial, from trying to convey the message in only 30 seconds to making sure all goes well on the day of the shoot. And I'll admit, it was more interesting than what happens on most other reality shows. (I'm not a fan of reality TV, in general.)
And true, having a live studio audience added a feel of excitement & tension to the show that was lacking before.
But of course the only end result was we got to see the inventors' visions on how their products would be marketed. They're still the same products from the last 4 episodes -- no different.