In the past I have seen 1.5X/2.0X playback in YouTube working on some YouTube videos.
To ensure this was not due to "old" YouTube videos, I chose a random 2014 Superbowl commercial. I cannot see any speedup playback controls.
https://www.youtube.com/user/mmschocolate?v=q3Z4TQKGXbE
I am using Chrome on OS X Mavericks.
Update After a half dozen attempts the speed setting is now showing up – on the same video it did previously.
I have no clue what has caused the speedup capability to reappear: I did not make any Settings changes in the interim.
Best Answer
Google youtube html5 - this will take you to a page that allows you to select html5 as the preferred player. HTML 5 = player - you have the speed option. Flash = player - no speed option.