my 2 pc - generally I agree with Anunaki, but there are battles worth fighting and I'm not sure this is one of them. I can't say that either side of the argument presented their very best and dragging AerLingus HR into this will put no-one into great light.
I don't think the video interview presented overly serious questions, in fact, I believe it's sole purpose is to check how good your English is and nothing else. These are the types of questions that you should have heard before if you ever attended a job interview. Of course you can prepare a little bit better if you know exactly what's coming but you will not hide a heavy accent, pronunciation difficulties or lack of vocabulary should you have such issues.
As for the 3000 applicants, I'm not sure where the number is coming from, is that from the applicant ref number? I just want to point out that AerLingus are also doing their cabin crew recruitment at the moment and they are running a similar process. When I applied for pilot position I saw 2 reference numbers, one was the ref number 3xxx and the other one was internal ref number which was just below 1000 (I applied close to the deadline). So I wouldn't be to quick in trying to guess how big of a competition you currently are up against unless the number is coming from a reputable source.
Even if they did receive 3000 applications, I can guarantee you there will be dozens if not hundreds of applications there that are not suitable - either form people who have no licenses at all (these openings were widely advertised here in Ireland and you could read on the comments in the media from people applying anyway thinking Aerlingus will put them on a cadet scheme) or people with expired ratings, people with ELP below 5, and of course the brigade of people who have no right to live or work in the EU
it's still a stiff competition alright, but I would worry less what few candidates do and worry more about the potential for AerLingus screwing up the whole process anyway similarly to what they've done in the past