Open your File Manager app and navigate to: Internal Storage > WhatsApp > Media > WhatsApp Video
WhatsApp videos are usually saved directly to your Photos app if "Save to Camera Roll" was turned on in 2019. VID-20190603-WA0039
Long-press the video in your gallery and select the Share icon to send it via email, Drive, or another messaging app. Open your File Manager app and navigate to:
💡 For example: Are you trying to recover a deleted video? VID-20190603-WA0039