**Tl;Dr: What's the most fundamentally UX friendly equivalent to a pre-roll video advertisement which doesnt involve an actual advertisement - only a prompt to pay to remove the inconvenience?**

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My UX question will require knowledge first of the app model, so I'll explain it briefly, and I apologize for the length of the detail but it's not the simplest question to ask. I suspect from the above question alone, people would ask for infinite elaboration, so I'll provide it below::

I'm about to launch an app, similar to a few others out there, that allows you to stream videos together as a group in sync, while exchanging voice chat. Youtube, Vimeo, any service that supports embedding. A synchronized video experience. The model is supposed to be free, supported by pre-roll video ads.

The catch is that my app *also* allows people to stream video content stored locally on their devices. Home videos, videos taken on their phones, cameras, etc, can be watched as part of this synchronized video sharing experience. But, although it wont be permitted according to our terms of service, people will be able to stream movies they download from the web, perhaps illegally.

That's just an unavoidable implication of allowing people to stream local content to each-other. And so, understandably, no advertisement agency that I've spoken with can permit their ads to be used in association with this application, as there's the possibility that it unfortunately may gain a reputation for being used in association with copyright infringement - watching pirated content together.

So to support a free model, I'm interested in creating, in concept, the equivalent of advertising (a brief inconvenience for the user, which the user trades as payment for the service), which inclines the user to buy a premium membership to skip this brief inconvenience for him/her and his/her party/group watching the video together. 

**My question is:** Is there a known method of using some inherent inconvenience to the user (other than advertising) which allows them to use the service for free, but still motivates them to potentially purchase a premium plan to remove said inconvenience? 

I ask because it seems like this might give me an opportunity to use the inability to advertise as an advantage to my UX experience. Instead of having to serve the user a whole video ad that they may or may not be interested in, I can instead utilize the most fundamental equivalent to this UX interruption without time requirements or specific content being displayed. In other words, I can engineer the inconvenience to be much less damaging toward the UX than the advertisement would have been, theoretically. 

I imagine this strategy might already be used in clever ways, but the closest version I can think of is the method of using "energy" in mobile apps to slow down your progress without payment - that's not what I'm looking for.