1. Make sure that the TV box and the mobile phone/computer are connected under the same Wi-Fi network.

2. Open the Tencent video application or webpage and log in to the account.

3. Click the "Projection Screen" button in the upper right corner of the video details page to search and select the video to be projected.

4. The system will automatically search and display the list of projective devices, and select the TV box.

5. After clicking the device name, the video will be played on the TV box.

Please note that the specific operation mode may be different due to different Tencent video versions and TV box brands. The above steps are for reference only.