Earlier quoted context omitted.
Without studying the minified code I wouldn't assume malice just yet, this could be just an inexperienced developer trying to lazily fix some browser-specific bug, or something that accidentally made it to production like you say
You think they let inexperienced developers touch the YT code base without proper code review? Even if that were the case, which is an extremely charitable assumption, that itself would be malice in my opinion.
This reply is for everyone who has ever worked on the codebase...