This Mac YouTube Downloader and Converter can automatically detect the YouTube video files from the YouTube web pages you have opened and download multiple files at a time.
As a YouTube Converter, it can batch convert YouTube videos to all other popular video/audio(AVI/MOV/MP4/MPEG/3GP/AAC/MP3...).
If you just download YouTube video without converting, you can use this free Mac YouTube Downloader and play downloaded video with free FLV player.
Share some helpful Mac Tips:
How to Make YouTube Collection and Play on DVD Player.