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. It supports MPEG-4 Part 10 (H.264) video codec and AAC sound.
RealPlayer, Apple QuicTime Player
VLC Media Player
HEVC (High Efficiency Video Coding), is a modern video compression standard developed as the successor to the standard H.264 (Advanced Video Coding). In comparison to H.264, this format offers up to 50% better data compression while providing improved video quality at a similar bitrate. Today, HEVC is used by over 40% of video developers, only second to AVC.