which is more efficient for work done per amp, AC or DC?

Twice now I have run across people stating that it is better to use the AC from the inverter than the DC from the system because the DC takes 8 - 10 times more power to drive something than AC. Since the statments  were made on videos I don't have a way to have them clarify this statement. You can hear the statement by going to the 13:15 time mark and listening: www.youtube.com/watch?v=Zimg0APaHI8

Clarification would be helpful as I was about to rip the ballast/starters out of led lamps to wire them directly to 12V. Plus I felt the heaters might work for my situation.

Thanks for any help.

gm