I've had experience with this through my startup, SuccessTelevision.biz.
Unless you're meeting a real business need, the videos don't get used. I think finding the management or HR need is very important and will co-opt managers into giving staff the time to watch the videos. Some of this will also depend on whether the videos are for hard-skills or interpersonal skills. Otherwise, there's too much distraction and no time for self-improvement.
Also, the videos have to be part of an overall training program, not just a "nice to have" stand alone. I've also found compliance video trainings: diversity, harassment, are very popular.