Asks for a scientific explanation of these phenomenon. My leaning is this is a 'good off-topic example'.
It's not a bad question because there are many claims throughout history of people believing and documenting seeing these things.
However, there are too many possible explanations for these. It could just be a kid hiding in the grass with a torch, someone lighting fireworks or some ancient guy taking hallucinogens.
To answer the two questions asked:
- Have any scientific inquiries determined the real cause of these lights?
No because the claims are not based in science
- Are there any credible photos or videos of the phenomenon?
No because the claims themselves are not credible
Nobody is going to perform a serious 'scientific' study on fairy lights. So this question cannot be sensibly answered.
The same question could be asked about dragons. It could be based on ancient people spotting elephants or crocodiles etc. and enough crazy people believe in them to make it a notable claim, but it is not practically answerable.