Not sure if this is a bug or a problem with the subtitle file itself:
If I try to select the โChinese (Simplified)โ subtitle in the โYoutube subtitle language settingโ for this video: Chinese Peppa Pig - ๐๐๐๐ฐ ๐๐ก๐จ๐๐ฌ ๆฐ้ๅญ - ๐ ๐๐ ๐๐๐๐ - YouTube, Iโm not getting dictionary lookup or vocabulary highlighting (among other things). When I simply choose โChineseโ it worksโฆ the pity is that this subtitle file contains also pinyin and the english translation which messes everything up.