You can't actually post the pictures here, and the rules state that you can't actually share your own private collection (ie which are copies of publicly available pics):

1) The following postings are forbidden and will be deleted immediately:
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1.06 links to groups (Yahoo etc.) and file sharing programs or sites;
...
1.10 links to websites which hurt any copyright laws (this is already the case if pictures have been copied to another website without permission);
....

So just post links to the original pictures.

(If you copy a picture for your own personal viewing, then you are probably just about OK as far as most country's copyright laws go. If you share them PRIVATELY with others, then you're probably also ok. But as soon as you 'publish' (ie share on a publicly accessible web site) them, they you have to pay $$$ copyright fees. Yes, there are a lot of people breaking the copyright laws out there, and many image sharing sites are cracking down, so they don't get sued. Same principle applies to audio & video, which is why YouTube are now very strict.)

Just because someone has posted something on YouTube, or any other site, does NOT make it 'public domain' at all.

I started to write a long reply (tl;dr!) all about copyright, instead try this: copyright is all about the original 'artist' making money for themselves. Why should they give it away for free? If YOU make money from something that *I* created, you can use it ONLY if you pay me - sounds fair to me.

Let's make it physical rather than something easily copyable: I have a PA system, you need a PA system. Pay me and you can either borrow it, or buy it from me. But for the moment, it's MINE! Just because I temporarily left it at a venue doesn't give you permission to use it, without asking!

So, if you post a link to the ORIGINAL site, then that original person might earn some money from it. Plus people can see their "other art", and they might make money from that too. Which might encourage them to make some more. However, if you just copy it, then YOU are making the money, with little or no effort needed (many people would use the word "leech")