You are downloading the Flat Tube XAP file v18.104.22.168 for Windows Phone. Flat Tube is a free and useful Entertainment app: Flat Tube is a YouTube client app for Windows Phone and Windows with the best flat design UI for user. This app allow user browse, watch, ... You can now download the offline XAP file to install & try it.
Download Locations for Flat Tube 22.214.171.124 XAP file
Note: To install it manually from an SD card, you should choose one of the server location above to get the offline Flat Tube XAP file, move the file to your phone's SD card and then tap 'Install local apps' in the phone's App list.