When I try to run video in Rekonq from Youtube, I click the icon in the lower right corner to make the video full screen and I get a pop-up indicating, "Your browser does not support full screen Learn More". Why is this? It is html5 video. I love this browser and the way it integrates with KDE but it does not have this ability in today's Internet media enable experience?

Hi. I don't know how to make it show in a fulscreen, but here is what I've done:
1) Clicked "widescreen" button on youtube-video
2) F11 to make a fullscreen-view of Reconq
3) Ctrl-Num+ to zoom in. Do it till the size of your video suits well.