You are downloading the Video Tuner APPX file v18.104.22.168 for Windows Phone. Video Tuner is a free and useful Productivity app: Video Tuner works best on phones running the Lumia Cyan software update. To get the latest software update for your phone, go to Settings > Phone ... You can now download the offline APPX file to install & try it.
Download Locations for Video Tuner 22.214.171.124 APPX file
Important Notice: Now Due To Unspecified Limitations, You Can Not Use The Offline APPX File To Install It Any More.
To try to install it manually from an SD card, you should choose one of the server location above to get the offline Video Tuner APPX file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.