Here is the video of the transfer:
As you can see, because she didn't have the time to maintain the top bar hive, it took several hours to transfer the colony to the deep middle bar hive because Stan Moulton had to cut out the comb individually. The flaws of the top bar hive are fairly obvious as you watch. The maintenance is difficult and harvesting honey is destructive to the comb. However, with a deep middle bar hive, harvesting honey is not destructive and there is no fear of the bees building comb that adheres to the wall and bottom of the boxes. Though there is maintenance involved with the middle bar hive, it is clearly much less than it is for a top bar hive.
You can purchase middle bar frames here and a deep middle bar box here.