Recently I ran into a funny problem viewing Youtube. I could not view full screen videos. Despite clicking the full screen button, the video would play at a larger display, about two thirds of the screen. Sometimes it would hang. This problem only happened with some of the videos.
I checked other browsers, and discovered that it was a problem unique to Chrome.
I found a solution to a similar problem on Wikihow, and was glad to see that it works on this problem as well.
Turns out Flash player installs more than one plugin. The problem is a result of a bug in one of the plugins. If you disable that plugin, the browser will use instead the other plugin with the aforementioned bug being resolved.
The Wikihow article has a full detailed howto, with screenshots, so I'll only summarize the solution here, and point where you need to deviate from their guidance:
1. Go to the plugins installed on Chrome (type URL: chrome://plugins/ )
2. Click the "Details" link on the upper right corner of the screen.
3. Locate the plugins of Flash Player (In my computer they were first on the list)
4. HERE WE DEVIATE FROM WIKIHOW:
Disable the "PPAPI" plugin (first on the list here, and if to deduce from Wikihow - in all Chrome installations).
It is important to understand that this change is not without a price. NPAPI is old technology. PPAPI is a new and considerably better architecture to glue a web browser and a native application. You can read more about it -
Sadly, if you browse the web, it seems that PPAPI is one of those examples where innovation is getting in the way of getting things done. I prefer this solution, which enables me to keep using Chrome as my main browser while at the same time being able to use youtube without a hindrance. As far as I can tell, others also choose disabling the PPAPI flash player plugin, as it gets in their usages of flash.
Another possible solution is using another browser. As far as I could check, neither Firefox, Internet Explorer or Opera had this problem...