By Bern Rexer
The YouTube Live Streaming Community on Google Plus has a category to post your feature requests.
It can be found here:
YouTube Live Feature Request
The Google Product Forums has a special YouTube Live topic user group. This is an active forum moderated by the YouTube live ops department for announcements and issues.
Although they don't respond to all posts you have a good chance of your request being seen by YouTube here.
I don't know of an official feature request submission form or email but maybe someone can leave a comment.