the only good thing about MOTs being used like that is that since there is no built in current limiting like in a neon transformer they tend to burn out very quickly when you're trying to draw an arc off them.
For a short time they will output WAY more current arcing than they ever would be delivering in an oven. The Tesla coil builder folks love to use them, but they do have to provide for some way to limit the current or they quickly die.
Just removing them from an old oven can be deadly too since there is a very large high voltage capacitor you have to remove as well.
There are also videos out there of people pulling arcs off of distribution "pole pig" transformers. Now that is something to see...
