One of the problems the official YouTube iPhone app has is that it will not let you play YouTube videos in HD over your cellular data; even if you have the fastest LTE connection, the video will be played in low quality. The YouTube iPhone app lets you change the quality of a video, but that option is limited to WiFi only. If you have unlimited data and want to watch YouTube videos in HD over your data, then you can enable HD on the YouTube official app by just downloading a tweak from Cydia. The Cydia tweak, named HD Enabler for YouTube, can be obtain from Cydia for $1.99 – just search it up and should appear on Cydia’s BigBoss default repo.
After downloading the tweak you don’t have to configure any options, you will have a new 720p option in HD videos.The tweak works with the YouTube official iPhone app which can be downloaded from iTunes App Store.