I bought two lights like these for 57$ each when they first started appearing on ebay/aliexpress. They're very bright, not 12000LM but 5000-6000LM seems plausible with freshly charged batteries. The output will diminish with the voltage of the batteries though. I left one light in a bucket of water on the highest setting, after 1.5 hours the light was still burning but the brightness was maybe 10% of what it was initially.
It is likely that the lights that are sold on ebay/aliexpress/amazon are earlier rejected versions of the light macado linked to above. I did buy a third light as a backup, but only one of my three lights have been working without any major issues.
I usually turn the lights on at the surface and leave them on for the remainder of the dive. However, with one of the lights I originally bought the button that controls the white led's will get pushed by the water pressure at around 25 meters depth, this turns the light off. The other two lights doesn't have this issue but the body/tail on the third light I bought is slightly shorter than on the other two and it doesn't make a proper connection with the board in the head unless you remove the innermost o-ring. What I did instead was using the body from the light with the faulty button, together with head from the light which had a shorter body.
I don't think you'll find a brighter video light than this one for less money, but the likelihood of receiving a faulty product is very high. If you decide to buy this light, make sure to buy it from a highly rated seller who will replace a faulty product.
There's a thread a few posts bellow which was started by me, in which there's a video that was shot using these lights.
