Zinc alternatives

Vookmark allows you to bookmark interesting videos with a single tap & watch them later anytime on any device

Play is the best way to bookmark YouTube videos to watch later on your iPhone, iPad, and Mac. Import or add using drag and drop. Search, filter, sort, and organize using tags. iCloud syncs everything. Add YouTube to your Home Screen, with Play's widgets.

tubeSeek allows users to recall YouTube videos that are in a foreign language and have foreign language titles/tags. You no longer have to depend on the thumbnails to remember useful videos in your playlists. Just tag with your own words using tubeSeek.