after becoming frustrated about having only two viewing size choices (standard/small or fullscreen) for watching ALL online videos, i thought it time to experiment...
it looks like you can just take the embed codes for any video, paste it into your browsers address bar, remove any of the embed tags that surround the url, then hit enter.
you'll then have the embedded video playing back in your browser - simply resize your browser to resize the video.
this is so simply it's probably been mentioned hundreds of times online already, but it was new to me. kind of obvious too when you realise pretty much all online vids have embed codes.