Vampire-Specific House Rules/General
Flaw: Cast No Reflection
The LaSombra have a clan weakness Cast no Reflection, and there is a Flaw Cast no Reflection. Under the description of the weakness, it specifically states they do not show up on any cameras, including digital ones. Although scientifically, digital media today do not use reflections, neither did security cameras at the time the books were written. Furthermore, this isn't a physical, scientific weakness or Flaw - it is a supernatural one, involved in the curse of LaSombra's blood and the poor unfortunate Kindred who have somehow inherited this Flaw without being LaSombra. This is fate, if you will, rather than an effect of the environment. So, those with LaSombra blood and the Flaw cannot be captured on film or by video feeds.
However, for your PC to know this, you would need to have LaSombra-lore 1, Sabbat-lore 2, or Kindred-Lore 4. If you do not have these lores, and you see a vampire with no reflection, it would play into the stereotype from Stoker, et al, and you cannot identify said vampire as LaSombra. However, for those who take the Flaw, the assumption that the Kindred is actually LaSombra would be a valid one.