If this is for a specific video format or a proprietary security camera system:
: Avoid "free download" sites that look like generic templates. Download Demo Player rar
If you are trying to view old game recordings (demos) for Counter-Strike : : The classic tool for .dem files. GeekPlayer : Often used for older versions of CS. If this is for a specific video format
Which are you trying to watch a recording from? Download Demo Player rar
: Try this first; it plays almost anything without needing a .rar pack.
: Use sites like GitHub or ModDB for gaming tools.