OK Lello as requested the light set up.
I did not mention the Metz in the kit used in the gallery as it could be confusing. The key thing with this stuff being flash duration. The Vivitar is able to get to 1/30,000 so good for freezing motion. The Metz best is 1/10,000 sec way to slow. Position of the lights had to take account of those speeds. If the Metz had lit the bulb then its speed would not have been suffucient to freeze motion.
Stray light would have created this effect - Vivitar stops motion but Metz does not, so anything the Metz exposed would be blurred.
I hope that makes sense.
Don