A secure video player is a video player built to enforce content protection: it plays DRM-encrypted streams, honors token or OTP authorization, applies dynamic watermarking, restricts by domain and device, and avoids exposing direct media URLs. It is the client-side component that carries a platform's protection rules to the viewer.
A secure video player is a player engineered to enforce content protection, not just to play files. It is the client-side piece that carries a platform's security rules to the viewer's screen.
A standard video element can play a file, but on its own it does nothing to stop downloading, sharing, or recording. Security comes from the surrounding stack, DRM, tokenized delivery, watermarking, that a secure player is designed to integrate.
A secure player is only as strong as the encryption and access control behind it. Evaluate the player together with the DRM and authentication it depends on, not in isolation.