Use VLC Media Player (it plays almost any .mp4).
Open your File Manager → Internal Storage → WhatsApp → Media → WhatsApp Video. VID-20181029-WA0107.mp4
Look back at your WhatsApp chat history from October 29, 2018 . Use VLC Media Player (it plays almost any
The filename is a standard system name generated by WhatsApp. It indicates the video was received or saved on October 29, 2018 . VID-20181029-WA0107.mp4