Does ad-free get used when we are F5ing like crazy when the forum is down?
No. An ad-free view is only used on a successfully loaded page of the forum. That includes the shop, your profile, using the search function, any post, or anything else on the forum. Error messages do not use up our ad-free viewing.
In all seriousness, the identity of the source of any DDOS attacks isn't usually disclosed publicly as it's only relevant to our systems team since they're responsible for identifying and blocking it. And that's assuming the source is a notable entity to begin with.