Hi Kevin! Excellent questions. "watch later" is a great feature, I use it mostly for shorter videos. The analogy of a bookmark versus a reading list comes to mind. The clipping feature allows you to save segments of videos, rather than whole ones. The other way we hope to differentiate ourselves in the near future by allowing you to clip anywhere on the internet, with any video platform, not just YouTube.
Not sure if you got a chance to checkout the video tutorial, but the idea is the video segments are parsed by keywords made by users, rather than video/audio recognition technology. Each segment of video is like a document with keywords, meta-data, etc. so we just run our search algorithm through that, and it's pretty standard from then on.