GOM Media Player
GOM Media Player comes from GOM Lab, and it is one of the best, free software you can have when you’d love to play almost every media file. It supports a wide range of video formats including MKV, FLV, etc along with standard media formats. Also, GOM Media Player has a number of advanced features when it comes to playback of files, such as the playback speed control, video effects, audio capture, A-B repeat screen etc. So, in short, GOM Media Player is an impressive software.
Talking of UI & Customization, GOM Media Player offers advanced-level customization that supports different skins! You can download skins from official GOM Player site and make GOM Player look like as you wish. Also, there is a codec finder that helps you find sufficient codecs online when there’s an uncommon file or if GOM Player lacks that codec. Despite all these, GOM Media Player will work fine with PC that runs Windows XP S2 or later.