You need WinRAR or 7-Zip (free/open source) to open .rar files.
Often includes a private, password-protected folder and a built-in player.
Use a universal player like VLC Media Player which can sometimes even play videos while they are still inside a .rar archive. To give you a more specific guide, could you tell me:
Converts 2D to 3D, supports hundreds of codecs (MP4, MOV, AVI, etc.), and requires no external codec packs.
If you are looking for the "Simplified Universal Player Encoder & Recorder," this is a classic Windows tool known for converting almost any video format.
Compressed files can hide executable viruses that activate once extracted.
Right-click the .rar file and select "Scan with [Your Antivirus]" before extracting.