<p>In an era increasingly challenged by misinformation and synthetic media, ensuring the authenticity and integrity of digital videos has become essential for preserving trust and accountability. This paper presents ViDApp, a Decentralized Application (DApp) for video integrity verification that combines immutable on-chain provenance anchors with scalable off-chain media management. The contribution is positioned as a deployment-oriented systems contribution rather than as a new hashing primitive or media-forensic detector. Specifically, ViDApp defines a trust-aware hybrid verification architecture in which integrity-critical evidence is anchored on Ethereum, while large binary storage and contextual metadata are delegated to Firebase through cryptographically linked references that are never trusted without re-hashing. This design enables client-side hashing, wallet-bound ownership, auditable verification, and responsive operation on both desktop and mobile devices. The paper formalizes the registration and verification workflow, details an on-chain role-based access control extension, and provides a systematic security and threat analysis for hybrid video provenance. The evaluation reports scenario-based prototype validation and separates measured/observed evidence from analytical claims about gas cost, latency, storage overhead, and scalability. Overall, ViDApp demonstrates a practical provenance substrate for user-accessible video integrity verification, while explicitly identifying the benchmark-scale experiments, stress tests, and privacy-preserving extensions required for future work.</p>