FLV (Flash Video) is a video container format developed by Adobe Systems and comes with a .flv filename format. FLV is primarily used to stream audio, video, and text data such as subtitles on sites like YouTube, Metacafe, and more. It supports MPEG-4 Part 10 (H.264) video codec and AAC sound.
RealPlayer, Apple QuicTime Player MPLayer VLC Media Player
AIF (Audio Interchange File/Apple Interchange File Format) is a sound format used on Windows. It comes with a .aif filename extension and .aiff when used on Mac. An AIF file features raw sound data like sample rate, bit depth, and channel (mono/stereo). This file format is also accepted on most CD writers.
File Viewer Plus Apple iTunes QuickTime Player Windows Media Player