Yes it does, it helps you in a way that your video will shop up in Google searches for your keyword.
Building backlinks for videos is great if you are going to promote products, because people will mostly search for product reviews and to check if product is scam.
Here is a good example how building backlinks can helps you :
https://www.google.ba/#hl=bs&site=&source=hp&q=GenF20&oq=GenF20&gs_l=hp.3...970.1901.0.2137.0.0.0.0.0.0.0.0..0.0...0.0...1c.SULsY6xoHlI&bav=on.2,or.r_gc.r_pw.&fp=83c8dc204439b3f5&biw=1920&bih=900
As you can see at the position #7 there is a youtube video. that video will not get better ranked on YouTube for keyword, but it will on Google, and the Google is, obv., way more important because people on YouTube are mostly looking for fun, not for buying.
As you can see on that video which i took for an example, video has been uploaded on 24th Jun this year and with only 500 views he already beat the web site : http://www.hghalftimereport.com/ which is already 4 years old !!!!!!