One common problem often shared between slow internet connections users is that YouTube deletes video buffer when player is switched to full screen or maximized.
When you start playing any YouTube video, the red bar starts filling beneath video player indicating the buffer status. This buffered video resides onto your computer hard-disk and you can even save it for viewing video offline. Now if you maximize, YouTube by default removes all buffers and starts to fetch it again in high resolution. This is particularly annoying because it interrupts the video playing experience as it starts loading again.
