2 questions on linkbuilding

1 - Related sites

I run a site in a very small niche. So here's my question: do links need to be in related niche websites? Or they just need to exist? For instance: i link from my personal blog to my private investigators blog. Is that a problem?

2 - Youtube links

I created a youtube video on animoto and submited to youtube. Then I placed a link on the description. Later, I used onlywire.com to submit it to several social networks. Is that ok? What should I do next?

Thank you

Related sites help, but they are not much more important currently (but probably will in the future)

Youtube links are NO-FOLLOW so they don't count, its good to get the traffic but not for a PR boost, make links on the profile part of forums or in blog commenting.

it would be more worthy to get links from similar site. Google obviously weigh this more than having links from unrelated sites.