I went to vimeo.com with the browser of my phone (Firefox). Started to watch a video, the video plays inside the browser. I checked if I had instant apps enabled in Settings (Apps, Advanced, Default apps, Opening links) and I did. Maybe it's because I'm using Firefox? Would it work with Chrome? Oh well, it really doesn't matter. If I want an app I'm installing it, otherwise it's perfectly fine not to have it. Actually, I prefer not to have too many things going on without me knowing.