Youtube videos open up in separate "Flash-Player windows" when in fullscreen

*cough* Good morning everyone.

To get straight to the point, recently, for whatever reason, everytime I'd try to play a video on Youtube and click it into fullscreen mode, there's problems.

Normally, I'd click on the fullscreen icon on the bottom right and it would do just that, become fullscreen.

Now, however, as soon as I click on it, it would go fullscreen for a brief second then exit leaving me with the same Youtube page I was on before. However, the video window which would typically be where the video's playing at is now black and empty, and believe it or not, the fullscreen video is actually still playing -- only in a separate window, outside of that browser! Except, for some reason, when I mouse over the icon of that browser in my taskbar and it shows the preview of all the browsers currently open, the fullscreen video (titled as "Adobe Flash Player") is open along with it; now, if I were to click on it, it would either do two things: nothing, and then disappear from the preview thing, appearing back in the video window on its Youtube page, or function as any other fullscreen video -- but only for a second's glance, because eventually I came to find out that, at some moments, it would just straight-up exit/minimize again, forcing me to re-open it, (that is, only leading to it exiting again and forcing me to re-re-open it and continuing like that until practically the video is already done) and is twice as choppy as usual, which was completely absent in the 'usual' fullscreen mode, before I found myself confronted with this peculiar mess.

I've done what I know I can without screwing anything up but nothing has worked. If anyone can provide some assistance here I would greatly, greatly appreciate it.

I currently use Windows 7, Adobe Flash Player ver. 11.4.402.287, and have tried this fullscreen-dissonance glitch (Just made that up right now, tbh) on Chrome, Firefox, and IE. The issue isn't as bad in IE, but for some reason still acts up. Same goes with Firefox, but the issue seems much less consistent, sometimes occurring sometimes not. The problem mainly pertains to Chrome.

(Also, I am by far and wide not the most tech-savvy person in the world and will not be up to speed with the technical terminology poured out here, unfortunately; but I do know most of the very, very fundamentals and will provide whatever info necessary as long as I can salvage for it, 'ey.)

[EDIT: After some further tests I can confirm that there are some variations in regard to how this glitch/issue unfolds. Sometimes, the separate window literally becomes a separate window and appears in the taskbar, sometimes it does open up successfully and works for a while but still remains choppy, etc. Kind of exasperating, iyam.]