I love it, especially how you summarized the key points in one or two sentences instead of going into lengthy stories. It seems the key strategies can be listed as follows: 1. Great video which demonstrates a good knowledge of the community (Dropbox) 2. Viral (aka sharing) features built in (Instagram) 3. Leveraging existing userbase (Instagram, Product Hunt) 4. Exclusivity (aka invite only) (Spotify, Facebook, Quora…
I'm glad that you like the content :) Thank you! I will add more content soon since I've gotten more resources from the comments too.