There's 57,000+ posts on these forums, and there's a huge amount of info if you use the search box above
Here's a thread on the topic of embedding videos responsively:
http://embedresponsively.com/ is a pretty powerful way to get a responsive embed code from Youtube.
To see info on creating objects that are flexible based on the browser width, visit: Tumult Hype Documentation
Here's info on embedding Youtube videos: Custom Video Embedding: Youtube, Vimeo, or hosted video files | Stopping Audio when exiting the scene
For getting started with Hype, start here: Tumult Hype — Support