YouTubePlayer: fix attribute error in leavePlayerConfirmed
(If due to some problem the existing service is not started then seek() calls GSOD because getCurrentService() returns None.)
-YouTubeVideoUrl: fix get_video_info request, thx remitamine
-Use getValue() and setValue() instead of value
-YouTubeUi: small optimization
-YouTubeUi: remove class variable self.text
-YouTubeMain: use one variable pageIndex istead of pageStartIndex and pageEndIndex
-YouTubeMain: intruduce variable pageToken
(I think it's better to use an understandable name than self.value[2].)
-YouTubeUi: fix missing whitespace around operator
-YouTubeMain: intruduce variables current and text
(It's better to use an understandable name self.value[0] and self.value[1].)