http://www.twitch.tv/gimpy21/c/6660374
The first 30 minutes or so is going over the new Mech Lab. The remaining 60 minutes is spent trying to break the Mech Lab.

Notable Mech Lab bugs can be found at:
35:50
1:07:00
1:21:00
And to be clear, I really do like the new Mech Lab. It just needs more polish and bug squashing before being officially released.