You grant to blend-exchange.giantcowfilms.com a worldwide, irrevocable, non-exclusive, royalty-free license to use, reproduce, adapt, publish, translate and distribute your user content in any existing or future media. You also grant to blend-exchange.giantcowfilms.com the right to sub-license these rights, and the right to bring an action for infringement of these rights.
This indeed is very heavy. I'm allowing them to do nearly anything with my blend file. Until now, I often recommended new users this service, as is usual here, but after reading this, have a bad feeling about it.
I understand that a website with user content need some kind of long-range rights to host and distribute this content. I know that this service is offered with best intentions and free of charge, which is greatly appreciated. But following these terms it would also be possible to sell all blends there, or am I wrong? What happens if giantcowfilms is sold itself? Couldn't the terms be narrowed down to what is just neccessary to allow permanent storage and for using them here on BSE?