About the Humble Bundle pack, I was just digging trough all the assets, each asset creator has a readme.txt in it's folder which says:
"You may **NOT** use the resources in this pack for creating games made with engines/programs other than RPG Maker series.".
This is really crap, i just thrown away $25. They could have informed us a bit better on this, assets are assets imho, however we use it is up to our self if we pay for it.