**Update 2017:** It is now also possible to change the speed in the YouTube app, by clicking the three dot menu when playing a video, and then selecting Playback Speed
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Other ways:

**Sharing the video to an external app**

* Download an external player that lets you control the speed, like _BSplayer_. 

* Then in the youtube app when you get to the video you want to watch click the _Share_ button and then select the player you want to use.  The external player will open and it will play the video you want, and you can control the speed in it.  


_Tip:_ you can also use this method to skip ads.  If you share the video to a different player you can watch it right away without having to wait if there's an ad. 

_Edit:_ I mentioned VLC and Dice Player as other options to control video speed, but looks like I can't share a video from the youtube app to play with them, at least on my phone

.

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**Using YouTube in a browser app (like Chrome) and running JavaScript**


This works for watching videos on _m.youtube.com_
on the Mobile Chrome browser (probably other browsers as well) 

When a video is playing, enter this into the URL bar

    javascript: document.querySelector('video').playbackRate = 2

_Note: you have to type out the "javascript:" keyword, because the browser might remove it if you paste it_

You can use any number for the playback rate, including decimals

_Tip:_ Speeding up videos this way could get laggy if you use a slower phone, and the max speed you are able to watch it smoothly might depend on your device capabilities. For this, you can also select a lower resolution for the video, or in the phone browser select Desktop Mode and then select a lower resolution video.

**Saving the code as a Bookmarklet** 

You can save JavaScript code in a bookmark (called a bookmarklet) so you don't have to enter it in the url bar

Create a bookmarklet, name it something like 'ySpeed', and paste this code into it, I added a prompt so it asks to "Enter the Rate" each time it is run: 

    javascript: document.querySelector('video').playbackRate = parseFloat(prompt("Enter Rate"));

then on your phone when you're watching a video on m.youtube.com, type 'ySpeed' into the URL bar, don't press enter, you should see your bookmarklet pop up as an option. When you tap it the code will run and you will see a popup to enter your speed (.5, 2.5, 3, etc)


*Instructions for Creating a Bookmarklet:*

You can create it from your desktop browser or from your phone browser

_On Desktop_

 * Right-click the bookmarks bar
 * Click _Add Page_
 * Edit the name, and type the javascript code (including "javascript:") into the URL field 
 * Select your _Mobile Bookmarks_ folder (optional) and then click save

_On Mobile Chrome_

 * On any page (that you haven't bookmarked already) click the three-dot menu button next to the address bar
 * Tap the star
 * Tap _Edit_ on the popup that shows up on the bottom of the screen. If you missed it then tap on the star again and it will take you to the _Edit_ menu.
 * Enter the name, select your _Mobile Bookmarks_ folder, and replace the content of the URL field with the javascript code (including "javascript:") 


Some more info on bookmarklets: http://www.labnol.org/software/google-chrome-bookmarklets/27894/