Are valid Print & Play of bystanders tokens of Scenary Packs and others???

Any cardboard element (character card, feat card, BFC card, bystander, etc) is valid under Print and Play.

That said, I don't know if the current Print and Play section at HeroClix.com is completely up to date.

No, it is not up to date yet. The last one I saw that was updated on it was the FI Horde tokens and some of the LotR, but nothing since.
That being said, some judges may allow you to make your own "P-n-P" by photocopying the tokens you have, but you'll have to ask your judge as they aren't normally allowed since they aren't official.

This is not completely correct. The Print and Play BST must only "not be different from a legal WizKids-released version of the element" (Player's Guide 1/29/14, section 7, page 1). Nowhere is it required that the source of the image be the WizKids website.

Huh... I did not realize that. Good to know I can just photocopy a new release to get more of them without having to buy more of them (which is surprising for WK).

Also, last I saw the bystanders for The Winter Soldier mini- game and DoFP Sentinel set were available for download.