It's both, but mostly licensing. Presto needs a way to decode any file it alters the speed of. Right now that's all done in .so libraries within the application. I've kicked around putting something together that could be downloaded and installed separately, but I've never figured out the technical details of doing so. It's also adding another layer, which is risky. There's also the time factor: I don't have anywhere near enough time to dedicate to Presto, so a lot of stuff that should get done doesn't.