Hi,I would suggest not to forget the Google Webmaster Guidelines, as they are updated frequently:
https://support.google.com/webmasters/answer/35769?hl=en
And youtube Google Webmasters help channel, for video guidelines, this will keep you updated. Recently there was a question to Matt, about linking multiple domains. As you can guess the answer was something like, if it's really worth to link it from a user point of view do it, anything else might be considered as spam.
Here are some videos:
https://www.youtube.com/watch?v=x0-jw_PfwtY
https://www.youtube.com/watch?v=JzaimchdNpM
To my opinion, from now on, anything that links or repeats too much, will be over optimization. I believe the task for google is to get people to act exactly the same online, as they would do offline. So to answer you question about linking, I would say, if you believe this link would be clickable and would help your user to find the content - it should be ok.
