Yes, the rules are pretty much the same in the EU as in the UK :)
Being part of the EU, the flying and operation of drones in Ireland is subject to European Union Regulation 2019/947.
In EU, the UAVs are split in 5 categories (from C0 to C4) based on their mass.
Also, the flights themselves are split in different categories based on their risk level. The three main categories are OPEN, SPECIFIC and CERTIFIED.
The OPEN category (with sub-categories A1, A2 and A3) does not allow any flying over people under any circumstance (no difference made between children/adults, etc). The only 'excpetion' being that for aircrafts less than 250g (C0), flying over uninvolved people is 'tolerated'.
Considering the drone in question weighs more than 250g (wich is more likely, as you commented above), the only way they could fly legally above people within the SPECIFIC category (or CERTIFIED).
Considering the moderate level of risk involved, flights in this category (SPECIFIC) require authorization before the operation. The permission is given by the Irish Aviation Authority (IAA) considering the mitigation measures identified in an operational risk assessment.
Now remains one question : did they have that authorization ? :)
EDIT: In addition to the authorization, the operator (not necessarily the pilot, more like the manager) needs to be registered and the actual pilot needs an (official) practical skill training and assessment (‘UAS Remote Pilot Competency Certificate’).