The internet is about links. I mention my friend’s work in a post and link to his website, while he links to my Youtube video; we engage in mass linking. 😀
You don’t really need permission to link to another blog or website in your content.
Why, because it sends traffic to them. Likewise, if someone links to you, it might send traffic your way. In fact, you’ll know it because most blogs have trackbacks.
It’s essentially an "acknowledgment. This acknowledgment is sent via a network signal (ping) from the originating site to the receiving site. The receptor often publishes a link back to the originator indicating its worthiness"
But you do need permission when you use other people’s content such as images, copy, and video (most folk are happy for you to embed their YouTube video; it’s remixing the video that’s tricky).
So what to do?