This actually wouldn't surprise me if this was true. Religious concepts, even negative ones, tend to have a very powerful effect on the viewer, even (especially) subliminal ones. It would in no way imply the existence of Satan, nor would it imply that Monster Energy has a Satanic ritual in the basement of their headquarters every Monday, but it may imply one or both of the following:
1.
Whoever is making this video is paranoid and seeing connections where there are none, something which can be done with just about everything, ever, OR:
2. The people behind Monster Energy are really good at advertising.
I, personally, favor the second conclusion.
EDIT: Also, you have to think about who Monster Energy is marketing to. What better way to give your drink a "bad boy" feel than literally implying it is somehow related to the Devil himself?