This is a feature first introduced with the Google Home. Asking Google to stream cat videos on your Chromecast is a pretty nifty feature. Amazon has caught up and will now let you do the same with any Fire TV devices you use to watch movies or stream TV shows.
Amazons Fire TV and TV Stick both have mic buttons that summon Alexa. Though, only these devices let you ask Alexa to open Fire TV apps or control the playback. Thanks to a software update, youll be able to control your Fire TV the same way you can with the Alexa remote by asking your Alexa speaker to do it. Youll be able to pause, resume, skip back or forward, or play the next episode.
The software update will hit Fire TV devices automatically when you reboot it or after its been idle for 30 minutes. If you want to update it manually, you can go to Settings > Device > About > and hit Check for System Update under the Software Version section.
Check the source link for all the details.