Do FinCEN regulations apply internationally?

In a limited capacity, it does. For example if you are in the MSB business (outside the US) and are working with a US based MSB/MTO, you, as an external (foreign) entity are now required to register with FinCEN.

FinCEN, to be brutally honest, isn't the best example of a financial regulator. The reason being is that FinCEN leaves too much grey area. Not everything is black and white (as with say the Canadian or UK or EU regulators). Part to blame is FinCEN's federal role and the fact that each State in the US, particularly their DFIs setup their own rules, etc. which at times can be contradictory.

FinCEN's regulations like the OFAC checks, or SAR (Suspicious Activity Reports) or CTR (Currency Transaction Reports), etc. are widely hailed as the based models on which the AML framework has been developed worldwide. However, since FinCEN is US concentric, only the good parts of FinCENs regulatory framework has been borrowed by many and implemented.

So, yes, it does have a global outreach in certain areas (MSB, MTO, OFAC, AML, CTR, SAR, etc.), but in many areas, it does not.