Youtube has a high PR level so yes backlinks from youtube can boost SEO.
Websites linking back to your youtube video will also help the position of your video.
The higher the PR of the website linking back to your video the better the algorithm will determine the ranking.
Try not to create too many backlinks from one website at once especially if it's inconsistent because google's new update will see through that and push you down the Search engine.. .
if you have any other questions concerning SEO PM me.. .