The Windows Phone app which has gone free next as myAppFree app of the day is AllTube Player Pro.
AllTube Player (ATP) is a music/video/photo app that allows you to search for music, video and photo easily.
AllTube Player Pro Features:
Multiple websites: YouTube, Dailymotion, Vimeo, SoundCloud and Flickr
Download audio and video
Like or comment on media, view subscription, playlist, favourites and more
Local playlist to organize downloaded media