I like to watch/listen to videos on my TV via chromecast from local files on my computer. Chromecast doesn't allow you to set the playback speed, so you have to watch videos at a real world pace (eek!). Fortunately greggman created this neat little plugin that does exactly what I need.
Free Open Source Chrome plugin called Video Speed Controller
Source Code is available on github
From the docs:
The speed controls are not showing up for local videos? To enable playback of local media (e.g. File > Open File), you need to grant additional permissions to the extension. In a new tab, navigate to chrome://extensions Find "Video Speed Controller" extension in the list and enable "Allow access to file URLs" Open a new tab and try opening a local file, the controls should show up
I also recommend changing the increase speed shortcut key to 'k' and decrease to 'j' if you're a VIM fan =) And make sure you enable local file access in the extensions screen as you have to explicitly set this.