OK well here we are getting into an area where there is disagreement, so just take this post as my opinion only, but I'll offer it.
Yes, these are real live bacteria cultures. The debate is because one school of thought (correctly) assumes that if there is anything in the tank available to bacteria to use, sooner or later bacteria will turn up that use it, so why dose bacteria.
The explanation I got from an overseas microbiologist who is also a reefer, is that a culture of many bacteria types, such as exist in a reef tank, are at war with each other, in many ways. There is competition for food, chemical warfare, direct attacks on each other, etc.
All this can result in that the tank can move towards being colonised by a few dominant bacterial types, but not nessecarily the BEST types to achieve what we want. Therefore, dosing live cultures of selected bacteria can assist bacterial biodiversity and effect efficient nutrient reduction, thereby enhancing not just coral colour but also the health of the tank generally.
I have heard only good reports from users of Prodibio, not one bad comment yet.
And yes, a live bacterial culture is an important part of the Zeovit system, although there are other components to zeovit, including a bacterial food, and other things. The Zeovit bacterial culture is claimed to include several bacteria that will ensure that, in the manufacturers words, a "chain" of nutrient breakdown will be maintained, along with supplying coral food.
However, every time I mention Zeovit an argument breaks out, I'm hoping that won't happen this time now the rules are being enforced, but doubt it.
What I'll say is that while some doubt the manufactureres claims by not only Zeovit, but other bacterial systems as well, there is no proven reason to doubt the claims, and as a user myself I can say that in real life practise, the product has done exactly what it states it will do.
UV and bacterial culture dosing should not be done on the same tank at the same time obviously, they are counterproductive to each other. Looks like some appear to be having success with UV, so a person could go with one, or the other. The Zeovit manual specifically states not to use UV while using Zeovit.
Having said all that, now that bacterial dosing is coming more into vogue particularly on some of the more spectacular tanks, new brands and products of it are being released all the time. Stick to the proven brands, there is nothing to stop some cowboy selling any old bacteria as a reef product.
Hope that's some use, my humble opinion only.