It is perfectly okay to make any modifications, and re-use any other content you want for just your personal use, as long as you NOT re-distribute it/post videos of it. So technically you can do it, but ONLY for your personal use, just do not re-release it without permission from Mr Railfan.
As for creative-commons works, you would need to attribute the original creators, and use the same license they used.
what do you mean? 
Most of the time, content has a regular license, which means that it can not be re-used without permission, but creative commons means that you CAN re-use it, as long as you give credit to the creator.
