Downloaded videos on mobile phones can only be played when basic requirements such as format, bit rate and frame rate are met.
In the case of online videos, it's also possible that the slow network speed leads to insufficient cache and failure to load the video.
Solution:
1. Verify whether the mobile phone is compatible with the video format.
Due to the wide variety of video formats, if the phone does not support a specific format, it cannot play on the device.
2. Check whether the original video file is normal.
You can use other devices to check whether it can be played. For example, if the video can't be played on a PC either, it may be that the video file has been damaged.
3. Assess the functionality of the video player.
There could be compatibility problems with the current video player. Try using alternative video players to attempt playback of the video.
4. Inspect the network environment.
For online videos, slow network speed and insufficient cache may also lead to the failure to load and play the video. You can change the network environment and try again.