Closed (moved)
Keep an eye on Shumway (Flash in JS)
Mozilla has a project to run Flash in Javascript without using the native plugin:
https://blog.mozilla.org/research/2012/11/12/introducing-the-shumway-open-swf-runtime-project/ http://mozilla.github.com/shumway/ https://github.com/mozilla/shumway
It doesn't sound like it can play Youtube videos yet. We'll want to keep an eye on it in case it ever can.
To upload designs, you'll need to enable LFS and have an admin enable hashed storage. More information