I would be a little suspicious of how geeky things that have labelled themselves as "geeky" actually are. Often self-assigned labels like that are marketing in some form and reflect who they want to attract rather than necessarily being an accurate description.
As for the two definitions listed in the question, in my view the second definition is the more relevant to the use of geek or geeky in the context that the question appears to focus on. Not that the two definitions are mutually exclusive, there's in fact a great deal of overlap.
Then there's of course also the never ending geek vs nerd debate, where the line is definitely blurry and where the typical definitions yet again have a good deal of overlap. I'll take the risk of dealing with these terms as almost synonymous, which will quite possibly upset someone.
More to the point, I don't think that having a Facebook account or even posting videos on Youtube qualifies as geeky in itself, both are quite normal these days (Facebook more so) and being geeky isn't really about the medium used for expressing yourself unless there's actually something to that choice of medium.
For instance, amateur radio as a medium may qualify as geeky/nerdy as the people involved are enthusiasts that have some knowledge of the technology, equipment, etc. but the average Facebook addict does not typically have any particular insight with regard to Facebook, they barely chose the medium in the first place and they could just as well have used something else.
Either way, I think that the main question really has to be: what content are these potential geeks actually posting? Are they expressing their enthusiasm and insight on some topic? Does their knowledge go beyond just scratching the surface? Then there's a good chance that they can be classified as geeks (and/or nerds), regardless whether they are talking about the lore of Lord of the Rings, the optimal strategies in some computer game, electronics design, computer hardware, car tuning, sports statistics, carpentry, etc.
Just as a point of reference, here's a Youtube channel that I would consider a prime example of a geeky/nerdy (by the second definition of geek from the question): EEVBlog.
As a note regarding the first definition of geek from the question, there's of course the possibility that someone who is a bit socially awkward prefers interacting with others online but that's quite possibly hard to tell from their online behavior and it's probably not something they would go out of their way to advertise.