Apple iOS 9 brings a major shift to company's policy and will now allow developers to create extensions that block web-content on their devices. There was no public announcement regrading the new feature but developers running iOS 9 have found the "content-blocking" feature enabled in their device's Safari browser settings as shown below.

New Content Blocker App Extensions for Safari (on iOS 9 and OS X El Capitan) allows targeting of subsets of web-content (display ads, images, navigation elements, popups, scripts, fonts, style sheets, media files, cookies etc.) blocking them from being shown or loaded.

One of the most convenient and fastest way to download videos from Youtube website in various formats has been "Easy Youtube Video Downloader" which is already available as a free web-browser extension for Mozilla Firefox and Google Chrome, the popular free browser addon is now ported to work with Apple Safari browser and is available for public download. Easy Youtube Video Downloader For Safari allows users to download Youtube videos to their computers for offline viewing in MP3, FLV, 3GP, MP4, 720p HD and 1080p Full-HD qualities.