It's been half a decade since I last used VLC and looked this up, but I'm certain there was a VLC staff member, perhaps a moderator, who explained the presence of these sidebar entries as measures to cover development cost.

  There are in fact not a lot of posts about this topic

You mustn't have looked very far ;)

Well, a couple of minutes on Google. I just looked at all results for "sponsored" on the forum and it is in fact the only thread that uses it in that sense.

I'm still waiting for any concrete evidence, as I am genuinely curious what kind of sponsorships of that kind there are, or were, if any.

You're fully aware I was making an assumption or a false recollection. There's absolutely no need for this adversarial tone.