From Advanced Knack:
AK-Player is a completely free media player download which allows you to watch any streaming video files from sites such as YouTube offline. When you watch a movie file over such a website, the stream is saved to your temporary Internet files folder which is usually hidden and hard to access. Not only that; most media players do not support the streaming media formats anyway. AK-Player, on the other hand, will search through every folder on your computer, including hidden and system folders and allow you to play these files offline without having to waste bandwidth by streaming them every time you want to watch them. AK-Player also supports almost every other media format out there. You can play multiple video files simultaneously, altering volume controls individually for each open window. The free media player download provides many unique features as well as a user friendly and intuitive 3D interface.
What's new in this version:
Version 7.0 has Offline Search feature which lets you watch video sharing Web site offline. Also has smart playlist for each open file highly attractive 3D Interface.