: Standard text messages typically limit video files to 3.5 MB .
If "18521.mp4" is a video you want to share with someone via text/DM on TikTok: 18521mp4
If you want to send an MP4 file as a text (SMS/MMS) or through a messaging app: : Standard text messages typically limit video files to 3
If you are trying to add text overlays to a video file for a post, you can do so through the built-in editors of most apps: 18521mp4
: Ensure your Direct Message settings are set to allow messages from "Everyone" or "Friends" in your Privacy settings.