Yaya DaCosta who is playing Mark Ruffalo's love interest in this summer's The Kids are All Right is also Esquire's Woman of Summer. They have done what I think can be easily modeled by an indie filmmaker to promote their film in a fun non-salesy way. It's also a great way to build a list or as a gift for a project you are crowdfunding. The best part is it utilizes a skill you already have.
Esquire has created a series of funny videos where Yaya gives you a short affirmation.
My problem with it is it seems I have to go to the site to get the affirmations unless you set up an RSS feed. It's much easier for people to remember to come to your site, if that's what you want, if you push something to them. I would never have remembered to go to Facebook in the early days if they didn't send me email notifications of activity.
Creating your own online video series
You could do exactly the same thing, enlist your leading lady or leading man to shoot a series of short affirmations. You could have them do it in character or out. If you are a director with a fun personality you could be featured in them yourself. Regardless of what the exact content is I would have people submit their email addresses or mobile numbers and push it directly to them. Collecting the info helps build your list of potential fans to continue to engage. Sending a series of affirmations is preferable to one because it keeps your film in their minds.
The cool thing I think about affirmations is that you are giving the subscriber something of value, even if it's only a laugh, as opposed to just a sales pitch for your film. What other spin do you think you could put on this?